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T ISTRY OF 
L , ACTICE 



BV 

. KEITT 

Chemist of South i xperiment Station, and l*rofessor of Soils, 

Clemson Agi « -al College, Clemson College, S. C. 



FIRST EDITION 
FIRST THOUSAND 



NEW YORK 

JOHN WILEY & SONS, Inc. 
London: CHAPMAN & HALL, Limited 
1917 



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COPYRIQHT, 1917 
BY 

T. E. KEITT 



APR 18 1917 



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PREFACE 



Life, food, and raiment are directly or indirectly de- 
pendent upon agricultural products. In the settlement of 
our country, land was abundant and people were few, con- 
sequently little thought was given to the needs of the 
increasing numbers of succeeding generations. As the land 
first cultivated lost its fertility, the tide of population turned 
westward where unlimited areas of virgin soil awaited the 
herds and plowshares of the settlers. But this fresh area 
has been occupied, and to maintain the fertility of those 
fields that are still productive and to restore those that have 
become exhausted is the problem now facing agriculture. 

The maintenance of the fertility of a productive soil 
demands the intelligent application of the principles of 
agricultural chemistry. The restoration of wornout fields 
is a difficult and costly undertaking. The successful farmer 
must reinforce his art by the application of the fundamental 
information derived from the study of chemistry, geology, 
botany, bacteriology, and entomology. 

Chemistry aids agriculture in many ways. By means 
of it, exact data are collected and the fundamental reasons 
for practical results are explained. Then, too, chemistry 
invents new or improves old methods of fertilization. The 
chemist analyzes soils, manures and vegetable products. 
The value of soil analysis to the practical farmer, perhaps 
formerly overrated, in more recent years has been under- 
rated. From a soil analysis the farmer can at least learn 
if his soil is unusually deficient in any important element. 
Chemistry also protects the agriculturist from the impositions 
of the unscrupulous fertilizer manufacturer. 

The thorough analysis of farm products enables the 

iii 



iv PREFACE 

farmer to know their composition, and how much of each 
element they contain. This analysis serves a two-fold 
purpose: First, the composition of a plant shows what 
elements, and what quantity of each, have been removed 
from the soil. This, in turn, determines what the soil 
must contain to grow plants in a healthy condition. Second, 
in feeding vegetable products to livestock, the composition 
of these vegetables must be known in order that the rations 
may be compounded correctly. 

Furthermore, chemistry explains how plants grow and 
are nourished. It shows the kind and the quantity of 
foods which plants require at various stages of their growth, 
and this guides the farmer in properly handling his crops. 
It teaches what purposes the different elements in the food 
supplied serve in animal economy and how the best results 
in animal feeding may be obtained with the least outlay 
of time, labor, and expense. 

The purpose of this text is to furnish the knowledge of 
the fundamentals of chemistry required for intelligent 
agriculture and to apply this knowledge to the art of 
agriculture and to the problems of the agriculturist. No 
attempt has been made to limit its scope to the study of 
soils, fertilizers, and manures, although these subjects are 
given careful consideration. In addition, such subjects as 
feeds, nutrition, sanitary water, boiler water, and insecti- 
cides, subjects in which not only the farmer, but the sub- 
urban resident is interested — are discussed in as non- 
technical language as possible. 

The student of this book is urgently requested to make 
a careful study of the first chapters; for in them has been 
given in as concise and elementary form as is practicable 
the chemistry applied in the chapters which follow. Each 
succeeding chapter requires a knowledge of the preceding 
chapter, consequently they should be studied in sequence. 

The author wishes to express here his indebtedness 
to Professor Charles M. Allen, Pratt Institute, for careful 



PREFACE V 

revision of the chapters on General Chemistry and the 
critical reading of the whole text, and to Dr. C. A. Peters, 
Amherst Agricultural College, for many helpful sugges- 
tions and criticisms. Acknowledgment is made to Mr. J. 
Ross Hanahan of Planters' Fertilizer Company for Figs. 
37, 38 and 39, to Mr. John S. Carroll of the German Kali 
Company for Figs. 40, 41 and 42 and 52-60, and to Dr. 
Wm. S. Myers of the Chilean Nitrate Propaganda for Figs. 
45-51. The following members of the faculty of Clemson 
College furnished photographs: Director J. N. Harper, Dr. 
F. H. H. Calhoun, Prof. W. A. Thomas, and Mr. F. G. 
Tarbox. Mr. T. C. Hough furnished valuable aid by mak- 
ing drawings. Director Thorne of the Ohio Experiment 
Station and Director Hartwell of the Rhode Island Experi- 
ment Station very kindly gave permission for the repro- 
duction of cuts used, to illustrate bulletins of their respective 
stations. Cuts from Farmers' Bulletins of the United States 
Department of Agriculture were reproduced as well as cuts 
from bulletins of the South Carolina Experiment Station. 

Standard books that bear on the subject have been 
freely consulted. Grateful acknowledgment is also due 
my father, Thomas W. Keitt, for valuable assistance in 
reading proof. 

T. E. Keitt. 

Clemson College, 1916. 



EDITOR'S NOTE 



This little text has been prepared in the belief that 
boys attending high schools in farming communities and 
those taking short courses in agricultural colleges should 
receive instruction in the chemistry applying to farm prac- 
tice. For such students, there is neither time nor oppor- 
tunity for the usual formal course in General Chemistry, 
followed by technical Agricultural Chemistry. A single 
elementary course combining the two is possible, in which 
the information furnished is definite, practical and reason- 
ably adequate. 

In such a combined course, the essential principles of 
Chemistry naturally come first, to be followed by their 
applications to the problems which arise in the life on a 
farm, in the growing of farm crops, or in the feeding and care 
of farm animals. This order has been followed by the author 
in the present text. It is believed that teachers in high 
schools attended by boys living on farms and in agricultural 
colleges giving short courses will find in The Chemistry of 
Farm Practice the text-book best suited to their needs. 
It should prove especially valuable, also, as a reference 
book for those interested in farming. 

The Editor. 



Vll 



TABLE OF CONTENTS 



CHAPTER I 



Elements, Atomic Weights, Molecules, Symbols, Molecular 

Weights, Oxidation, Reduction 1 

Chemistry — Elements — Composition of Matter — Atomic 
Weights — Molecules of Elements — Symbols — Molecular 
Weights — Oxidation — Combustion — Kindling Temperature — 
Spontaneous Combustion — Reduction . 

CHAPTER II 

Compounds, Mixtures, Valence, Formulas and Equations 13 
Conservation of Matter — Compounds — Mixtures — Valence 
— Formulas — Hydrates — Criss-cross Rule — Equations. 

CHAPTER III 

Acids, Bases, Salts, Anhydrides, Dissociation, and Nomen- 
clature 24 

Groups of Elements — Classes of Compounds — Acids — Bases 
— Salts — Anhydrides — Dissociation — Nomenclature of Com- 
pounds. 

CHAPTER IV 

The Elements Necessary for Plant Growth 32 

Oxygen — Hydrogen — Carbon — Nitrogen — Phosphorus 
— Sulphur — Potassium — Calcium — Magnesium — Iron. 

CHAPTER V 

Water, Springs, Wells, Hardness and Household Water. ... 44 
Properties of Water — Solvent Action of Water — Availability 
of Plant Food — Drinking Water — Hardness in Water — Fil- 
tered Water — Boiled Water — Distilled Water — Boiler Water. 

ix 



x TABLE OF CONTENTS 

PAGE 

CHAPTER VI 

Soil Water 59 

Water Requirements of Plants — Soil Components — Soil 
Water. 

CHAPTER VII 

Air in Soils 63 

Composition of the Atmosphere — Soil Air — Effect of Car- 
bon Dioxide on Decay — Oxygen Must be Present — Factors 
Affecting Soil Air — Means of Producing a Change of Soil Air. 

CHAPTER VIII 

The Assimilation of Plant Food 70 

Sources of Plant Food — Osmosis — Function of the Leaves 
of Plants — Leaching. 

CHAPTER IX 

The Formation, Composition, and Fertility of Soils 76 

Formation of Soil — Composition of Soils — Gain and Loss 
of Plant Food — Importance of the Rotation of Crops — 
Proper Sequence of Crops — Use of Manures — Keeping the 
Land Covered. 

CHAPTER X 

Animal Manures 92 

Quality — Liquid Manures — Rotted Manures — Effect of 
Exposure to the Weather — Rate of Application. 

CHAPTER XI 

Agricultural Lime 97 

Sources of Lime — Effects of Lime on the Soil — Shipping 
Lime — Applying Lime to the Soil — Machine for Applying 
Lime — Gypsum . 

CHAPTER XII 

Phosphorus 107 

Presence in the Soil — Commercial Sources — Phosphate 
Rock — Acid Phosphate or Super Phosphate — Thomas Phos- 
phate or Basic Slag — Bone — Mineral Phosphate — Guano — 
Purchase and Application of Phosphorus. 



TABLE OF CONTENTS Xl 

PAGE 

CHAPTER XIII 

Nitrogen 120 

Importance of Nitrogen — Commercial Nitrogen Profitable 
— Selection of Source of Nitrogen — Inorganic Sources of 
Nitrogen — Saltpeter — Sodium Nitrate — Calcium Nitrate — 
Ammonium Sulphate — Organic Sources of Nitrogen — Vege- 
table Sources. 

CHAPTER XIV 

Sources and Use of Potash Salts 137 

Occurrence — Wood Ashes — Organic Sources of Potash — 
Minor Sources — Commercial Salts of Potash — Functions of 
Potash — Use of Potash on Different Soils — Selection of the 
Source of Potash — Tendency to Use too Much Potash. 

CHAPTER XV 

Measuring Plant Food Requirements 152 

Forms of Plant Food — Soil Analyses — Field Tests. 

CHAPTER XVI 

Mixing of Fertilizers 162 

Advantages of Home Mixing — The Calculation of Formulas. 

CHAPTER XVII 

Animal Nutrition 174 

Purposes of Animal Food — Classes of Foods — Development 
of the Science of Animal Nutrition — Digestible Nutrients — 
Metabolism — Rations for Various Purposes. 

CHAPTER XVIII 

Feeds and the Calculation of Rations 184 

Corn — Oats — Barley — Dried Brewers' Grain — Rye — 
Wheat — Rice — Cottonseed Meal — Linseed Meal — Meat 
Scraps — Dried Fish — Blood Meal — Soy-bean Meal — Pea- 
nuts — Timothy — Cereals — Legumes — Composition and Diges- 
tibility of Feeds — The Calculation of Rations. 

CHAPTER XIX 

Milk and Its Products 198 

Milk — Danger from Infected Milk — Preservatives — The 
Detection of Formaldehyde in Milk — Detection of Boracic 
Acid — Testing Milk for Per Cent of Fat — Determination of 
Specific Gravity — Ash — Butter — Cheese — Condensed Milk. 



xii TABLE OF CONTENTS 



CHAPTER XX 

Insecticides, Fungicides and Disinfectants 212 

Two Classes of Injurious Insects — Injurious Fungi — 
Insecticides for Biting Insects — Insecticides for Sucking 
Insects — Fungicides — Common Disinfectants. 

CHAPTER XXI 

Paints and Whitewashes 225 

Paints — Drying Oils — Driers — White Pigments — Green 
Pigments — Blue Pigments — Red Pigments — Yellow Pigments 
— Brown Pigments — Black Pigments — Mixing Paints — White- 
washes — Calcimine — Varnishes — Shellac — Glue. 

CHAPTER XXII 

Materials Producing Heat and Light. Fire Extinguishers 233 
Petroleum — Kerosene — Gasoline — Acetylene — Fire Extin- 
guishers. 

CHAPTER XXIII 

Concrete 239 

Use — Cement Manufacture — Setting of Cement — Sand — 
Gravel — Quantity of Material for Different Mixtures — Mix- 
ing Concrete — Placing the Concrete. 



THE CHEMISTRY OF FARM PRACTICE 



CHAPTER I 

ELEMENTS— ATOMIC WEIGHTS— MOLECULES— SYMBOLS- 
MOLECULAR WEIGHTS— OXIDATION— REDUCTION 

1. Chemistry. Chemistry deals with the composition 
and properties of substances and the changes which sub- 
stances undergo. Agricultural chemistry has to do with 
the application of the knowledge gained through chemistry 
to the art of agriculture and to the problems which the 
farmer has to solve. To understand agricultural chemistry 
we must gain first a knowledge of some of the underlying 
principles of General Chemistry. 

2. Elements. Matter is made up either of simple ele- 
ments or of these elements combined into compounds of 
unvarying composition. An element is a simple substance 
which has certain definite properties and which has not 
been separated into substances having different properties. 
Iron is an element. However minutely the piece of iron 
may be divided, the smallest particle will always have 
properties identical with the iron before its division. 

Somewhat more than eighty elements have been isolated 
which have resisted all the attempts of present chemical 
methods at further separation. Each element has certain 
distinctive properties that prevent it being classed with 
other elements, although certain elements which are closely 
related have some of their properties in common. 

Only ten elements are necessary to sustain the life of 



2 • CHEMISTRY OF FARM PRACTICE 

the growing plant; these are carbon, hydrogen, oxygen, 
nitrogen, phosphorus, sulphur, potassium, magnesium, cal- 
cium and iron. Some of these elements are derived from 
the atmosphere, some from water and some from the soil. 
Most of the substances of plants consist of the elements, 



OXYGEN 
49.8* 


SILICON 
26.156 


ALUMINIUM 7.3* 


IRON 4.1* 


CALCIUM 3.2* 


SODIUM 2.3^ 


POTASSIUM 2.3* 


MAGNESIUM 2.2* 


ALL OTHER ELEMENTS 2.7* 



Fig. 1. — Percentage of elements in the combined mass of atmosphere, 
waters and crust of the earth. 



carbon, hydrogen, and oxygen, which are obtained from 
the atmosphere, or from water. Nitrogen is the most 
expensive and the most elusive of the elements required 
by plants. A part of the nitrogen may be derived from 
the atmosphere by certain plants under conditions we 
shall study later, but most of the nitrogen which serves as 



ELEMENTS— ATOMIC WEIGHTS— MOLECULES, ETC. 3 

plant food comes from the decomposition of organic sub- 
stances in the soil. The other six elements necessary for 
plant growth are required in comparatively small amounts. 
With the exception of phosphorus, soils usually contain 
an abundant supply of these " ash elements." 

In the diagram, Fig. 1, is shown the relative propor- 
tion of eight of the most abundant of the elements as found 
in the atmosphere, all waters, and the solid parts of the 
earth's crust which have been examined. It will be noticed 
that the seventy-five elements not mentioned, altogether, 
comprise but 2.7 per cent of the earth's constituents. With 
the exception of a comparatively small quantity of oxygen 
existing in a free condition in the air, this figure represents 
the percentage of the elements as they exist in compounds. 

3. Composition of Matter. Matter may be divided and 
subdivided till definite parts called molecules are reached. 
Finally the molecule, by chemical means, may be separated 
into invisible particles called atoms. The atom may be 
defined as the extremely minute particle of matter that 
enters as a unit into chemical combinations with other 
atoms. A molecule is the smallest part of matter that can 
exist by itself. An atom does not remain free or uncom- 
bined; it unites either with other atoms of the same kind 
to form a molecule of an element or it combines with atoms 
of a different kind and thus produces a compound. 

4. Atomic Weights. Atoms combine chemically accord- 
ing to definite proportion by weight, The smallest amount 
of hydrogen that will enter into chemical reaction, i.e., 
the hydrogen atom, is less by weight than the atom of 
any other element. For this reason hydrogen may be 
taken as a convenient unit of comparison and its smallest 
combining weight, which is the weight of its atom, may 
be assumed to be one. The gases hydrogen and chlorine, 
when mixed and exposed to light, will form a new substance, 
hydrogen chloride, which in its water solution is called 
hydrochloric acid. When one part by weight of hydrogen 



4 CHEMISTRY OF FARM PRACTICE 

is allowed to unite with an excess of chlorine, it is found 
that it will, in every case, combine with 35.46 times its 
own weight of the chlorine. Hydrogen chloride therefore 
contains hydrogen and chlorine in the proportion of 1 
to 35.46. There are reasons for believing that the mole- 
cule of hydrogen chloride consists of one atom of hydrogen 
combined with one atom of chlorine. If this is true, then, 
taking the hydrogen atom as a unit of weight, the chlorine 
atom weighs 35.46 and the molecule of hydrogen chloride, 
HC1, weighs 36.46. It has been found that the elements 
which compose a compound always combine in propor- 
tion to their atomic weights or to some multiple of their 
atomic weights. It will be seen that this must be the 
case if an atom is indivisible. 

The atomic weight of an element is fixed by deter- 
mining with great care the weight of the element that will 
unite with another element whose atomic weight has pre- 
viously been determined. As nearly all the elements form 
compounds with oxygen, while comparatively few unite 
with hydrogen, the atom of oxygen with an assigned weight 
of 16 is really used as the standard instead of the atom 
of hydrogen, which it will be observed in the table on page 
6, weighs 1.008. 

5. Molecules of Elements. The common elementary 
gases, such as oxygen, hydrogen, nitrogen, and chlorine, 
have molecules consisting of two atoms of each element. 
The molecules of some of the elements, such as phosphorus, 
arsenic, and antimony, have four atoms in each molecule, 
when they are at a temperature slightly above vaporiza- 
tion. In most cases the number of atoms in a molecule 
of an element depends upon its temperature. Thus sul- 
phur vapor at 468° C. has eight atoms to the molecule; at 
830° C. its molecule has but two atoms. 

Some elements, such as sodium, potassium, mercury, 
and zinc, when in a vaporous state, have but one atom 
to each molecule. Such molecules differ from atoms in 



ELEMENTS— ATOMIC WEIGHTS— MOLECULES, ETC. 5 

that they seem to have lost the chemical affinities which 
are characteristic of atoms. The number of atoms in a 
molecule of an element when it is in the solid condition 
is not known. 

6. Symbols. For the sake of convenience, each element 
is represented by one or more letters. This abbreviation 
of the name of an element is called its lymhcl. The letter 
used to represent an element is often the first letter of its 
name. It is written as a capital, but unlike other abbre- 
viations, it is not followed by a period. The symbol of 
oxygen is 0, of hydrogen is H, of nitrogen is N, and P 
is the symbol of phosphorus. When the name of more 
than one element begins with the same letter, the most 
important or the first discovered of these elements has the 
single letter for a symbol and to the others an additional 
letter is assigned. Thus C is the symbol for carbon, Ca 
the symbol for calcium, CI the symbol for chlorine, Cr for 
chromium. It will be noted that the second letter is not 
written as a capital. Sometimes the symbol is derived from 
the foreign word which means the element, as Fe from 
the Latin ferrum, meaning iron, K from Kalium, the Ger- 
man word meaning potash, which contains potassium, 
Hg from the Greek, hydrargyrum, meaning " water silver," 
a good description of mercury. Many symbols are taken 
from the names of countries, as Cu, copper, from the island 
of Cyprus, Mg, magnesium, from Magnesia in Asia 
Minor. The symbol of an element represents not only 
the name of the element, but it means also one atom of 
the element and consequently is a definite weight. S 
stands not only for sulphur, but for one atom of sulphur, 
which weighs 32, or two times the weight of an atom of 
the standard, oxygen. 

7. Molecular Weights. One method for determining 
molecular weights depends upon an hypothesis proposed 
by Avogadro, which has been quite universally accepted. 
This hypothesis states that " under the same conditions 



CHEMISTRY OF FARM PRACTICE 



TABLE I.— THE COMMON ELEMENTS 



Elements. 



Symbols. 



Atomic Weights Usual Valence 



Aluminium . 
Antimony. . 

Arsenic 

Barium .... 
Bismuth.. . . 

Boron 

Bromine. . . . 
Calcium. . . . 

Carbon 

Chlorine. . . . 
Chromium. . 

Cobalt 

Copper 

Fluorine. . . . 

Gold 

Hydrogen. . 

Iodine 

Iron 

Lead 

Lithium. . . . 
Magnesium. 
Manganese . 
Mercury. . . 

Nickel 

Nitrogen. . . 
Oxygen. . . . 
Phosphorus. 
Platinum. . . 
Potassium . . 
Radium. . . . 

Silicon 

Silver 

Sodium. . . . 
Sulphur 

Tin 

Zinc 



Al 

Sb 

As 

Ba 

Bi 

B 

Br 

Ca 

C 

CI 

Cr 

Co 

Cu 

F 

Au 

H 

I 

Fe 

Pb 

Li 

Mg 

Mn 

Hg 

Ni 

N 

O 

P 

Pt 

K 

Ra 

Si 

Ag 

Na 

S 

Sn 

Zn 



27.1 


3 


120 . 2 


3 or 5 


74.96 


3 or 5 


137.37 


2 


208.0 


3 


11.0 


3 


79.92 


1 


40.07 


2 


12.0 


4 


35.46 


1 


52.0 


3 


58.97 


2 


63 . 57 


2 


19.0 


1 


197.2 


3 


1.0C8 


1 


126.92 


1 


55.84 


2 or 3 


207.1 


2 


6.94 


1 


24.32 


2 


54.93 


2, 4 or 6 


200.6 


1 or 2 


58.68 


2 or 3 


14.01 


3 or 5 


16.0 


2 


31.04 


3 or 5 


195.2 


2 or 4 


39.1 


1 


226.4 


2 


28.3 


4 


107.88 


1 


23.0 


1 


32.07 


2 


119.0 


2 or 4 


65.37 


2 



ELEMENTS— ATOMIC WEIGHTS— MOLECULES, ETC. 7 

of temperature and pressure, all gases have the same number 
of molecules in equal volumes." While it is quite impos- 
sible to isolate and weigh a single molecule, yet if we select 
as a standard of molecular weight a molecule of oxygen, 
consisting of two atoms, and assign to it a weight of 32, 
we may, by assuming the Avogadro hypothesis, obtain 
the weight of the molecule of any gas. This is done in 
the case of ammonia by weighing equal volumes of ammonia 
and of oxygen under the same conditions of temperature and 
of pressure, and solving for the molecular weight of ammonia 
in the proportion: 

Weight of volume of oxygen : weight of same volume of 

ammonia = 32 : molecular weight of ammonia. 

In this manner we may determine accurately the weight 
of the molecule of any element or of any compound which 
may be weighed in a gaseous condition. 

8. Oxidation and Reduction. An understanding of the 
principles of chemistry involved in the processes of oxidation 
and of reduction is important. It is impossible to obtain 
a working knowledge of chemistry without gaining a mastery 
of these processes. A simple case of oxidation takes place 
when a bright strip of iron is heated over a flame. The 
oxygen of the air, more active at the high temperature, 
combines with the metallic iron, rusting it into a black 
oxide of iron. If a silver spoon is exposed to the fumes 
of sulphur, the silver combines with the sulphur and black 
silvsr sulphide is formed on the surface of the metal. This 
is also a case of oxidation, although here there is no oxj^gen 
involved. 

Oxidation may be defined as the combination of oxygen, 
or of other elements that act chemically in the same way 
as oxygen, with other material. Sometimes oxidation takes 
place in two or more stages. Thus metallic mercury will 
be oxidized by combining with one atom of chlorine, form- 
ing white mercurous chloride or calomel, which, in turn, 



s 



CHEMISTRY OF FARM PRACTICE 



may be further oxidized by adding to itself another atom 
of chlorine, forming mercuric chloride or corrosive sub- 
limate. 

9. Combustion. Oxidation produces heat as a result 
of the chemical action taking place. Should oxidation be 
sufficiently rapid to produce enough heat so that light is 
evolved, the process is termed combustion. When the 
materials entering into combustion are gases, a flame is 
produced. Burning wood is undergoing combustion, this 
process of oxidation being supported by the oxygen drawn 
from the atmosphere entering into rapid union with the 
hydro-carbon gases produced from the heated wood. The 
three conditions necessary for combus- 
tion are first, a combustible substance; 
second, a supporter of combustion; 
third, a kindling temperature. Usually 
carbon or hydrogen or some of their 
numerous compounds or the metals that 
are easily oxidized are regarded as the 
combustibles, while oxygen or some of 
the elements that act chemically like 
oxygen are considered the supporters of 
combustion. The material entering into 
chemical reaction which is the more 
abundant is likely to be considered the 
supporter of combustion, and thus the 
combustible and the supporter of com- 
bustion may exchange places. 

This is seen in the reversal of flames 
effected by the apparatus in Fig. 2. The 
lamp chimney is fitted with corks and tubes 
as in the figure. The straight glass tubes 
at A and C are at least ■£$ of an inch in internal diameter. 
The glass elbow D is connected with the illuminating gas 
supply. While the finger is placed at C, closing the tube, 
the gas is turned on and allowed to flow till the chimney 




Fig. 2. — Apparatus 
for showing re- 
versal of flames. 



ELEMENTS— ATOMIC WEIGHTS— MOLECULES, ETC. 9 

is surely full of gas, which is escaping at A. The gas at A 
is now ignited and the gas cock turned down till a small 
inverted flame is produced at A. The finger is now removed 
from C and the flame at A will be seen to ascend the tube 
and to burn at B. The gas issuing at C is immediately 
ignited. If we consider these two flames, we shall see 
that the one at C is composed of illuminating gas burning 
in an atmosphere of air, and naturally the oxygen of the 
air would be considered the supporter of combustion, 
while the gas would be considered the combustible. The 
flame at B is composed of air coming up the tube from A 
which is burning in an atmosphere of illuminating gas, 
and in this case we should naturally consider the illuminating 
gas as the supporter of the combustion while the oxygen 
of the air is the combustible. 

10. Kindling Temperature. While oxidation may take 
place at any temperature, in order to start and to con- 
tinue combustion, it is necessary for the combustible and 
the supporter of combustion to be at a certain tempera- 
ture, known as the kindling temperature. Each substance, 
under the same conditions, has its own definite kindling 
temperature. Phosphorus has a very low kindling tem- 
perature, taking fire spontaneously in the air. This is due 
to the fact that oxidation raises the temperature of the 
phosphorus to its kindling point. If a bit of phosphorus 
as large as a wheat grain is dissolved in a small amount 
of carbon disulphide and the solution poured upon a filter 
paper placed in an iron ring, as soon as the carbon disulphide 
evaporates, the phosphorus will burst into flame. In this 
case the finely divided condition of the phosphorus exposes a 
relatively large surface to oxidation. When a candle flame 
is extinguished by blowing upon it, the blast of air cools 
the flame below its kindling point. 

The quantity of heat produced by combustion will de- 
pend upon the quantity and the character of the gases 
entering into reaction, while the degree of heat will depend 



10 CHEMISTRY OF FARM PRACTICE 

upon the nature of the combining substances and upon 
how intimately the combustible and supporting gases may 
be mixed at the point of ignition. Hence a blast is used 
to provide a large quantity of oxygen which is introduced 
into the interior of the combustible gas, which is then 
forced to combine internally with the air of the blast and 
externally with the oxygen of the at- 
mosphere. The hole near the base of 
the Bunsen burner, Fig. 3, is required 
to supply air for combustion. The 
blacksmith's forge, Fig. 4, must be 
equipped with a " blower " to furnish 
|M| admiTlir enough air for the complete combustion 

Hjfesaiia of the large amount of gas. 
^IIIJjjL Gas Iutake In many cases the oxidation is a 

^fcJBIP slow process. This may be seen in the 

„ rusting of iron, the tarnishing of copper, 

Fig. 3.— Bunsen & ' . ° + w • 

burner tne dulling °* zinc - When ink that is 

pale when first applied becomes dark 

upon exposure, the ink has undergone oxidation. When 

paper turns yellow with age, it is being slowly oxidized. 

Almost everything we see about us has been oxidized. 

Besides the noble metals, such as gold and platinum, it 

is only thoss substances that have been artificially deprived 

of their oxidizing constituent that exist in any other than 

an oxidized condition. 

The rapidity with which oxidation takes place does not 
affect the total quantity of heat produced. An iron wire 
may be burned in a jar of oxygen and the combustion may 
last but a few seconds, or the wire may be rusted by exposure 
to moist air, and the oxidation may take a month to complete 
itself, but when the two actions are complete, if the same 
iron oxide is finally produced and in the same quantity, 
the total amount of heat will be identical in the two cases. 
Although combustion cannot take place without light, 
yet light may be produced by other means than com- 



ELEMENTS— ATOMIC WEIGHTS— MOLECULES, ETC. 11 

bustion, as in the case of the carbon filament of an electric 
light bulb. 

11. Spontaneous Combustion. If the heat produced in 
slow oxidation is not allowed to be dissipated, the tem- 
perature of the combustible which is being oxidized may 
gradually be raised till it attains its kindling temperature 



Blower to 
Supply Air 




Fig. 4. — A down-draft forge. 



and it will then burst into flame. This is quite likely to 
happen in the case of vegetable or animal oils with which 
cloths may have been saturated. These oils are " drying 
oils," that is, they are easily oxidized as shown by the 
necks and stoppers of their containers, which are gummed 
upon standing. This combustion is produced spontane- 
ously, that is, by the internal development of heat without 



12 CHEMISTRY OF FARM PRACTICE 

the action of an external agent other than the Oxidizer. 
Heaps of finely divided coal may in the same way be set 
on fire by the spontaneous combustion occasioned by the 
oxidation of their sulphur or oil content. 

12. Reduction. This process is the reverse of oxidation. 
It is the subtraction from a compound of oxygen or of the 
element which plays the role of oxygen. The extraction 
of the common metals from their ores is a process of re- 
duction. This process is brought about by subjecting the 
material to be reduced to certain reducing agents which 
have a stronger affinity for the oxygen part of the compound 
than does the metal originally combined with that part. 
The most useful of these reducing agents are carbon, in 
the form of charcoal or coal, hydrogen and the hydro-carbon 
compounds and certain active metals, such as sodium or 
aluminium. Carbon monoxide gas, which needs more 
oxygen so as to make itself into carbon dioxide, a more 
stable compound, is a very valuable reducing agent. In 
the highly heated areas of the blast furnace in the process 
of iron reduction, the carbon monoxide takes away the oxy- 
gen of the iron ore and leaves metallic iron. 



CHAPTER II 

COMPOUNDS— MIXTURES— VALENCE— FORMULAS- 
EQUATIONS 

13. Conservation of Matter. Chemical changes neither 
create nor destroy matter. By chemical means matter 
may be converted into new forms having different prop- 
erties, but the total weight of the substances before chemical 
action will equal the total weight of the substances after the 




Fig. 5. — The black solid, carbon, combined with the yellow solid, 
sulphur, forms the colorless liquid carbon disulphide. 

action has been completed. Sulphur, when burning, com- 
bines with the oxygen of the air, and when the sulphur is 
entirely consumed, the weight of the choking fumes of 
sulphur dioxide produced will exactly equal the sum of 
the weights of the sulphur burned and the oxygen with 
which it combined. 

14. Compounds. Two or more elements when chem- 
ically combined form compounds. A chemical compound 

13 



14 CHEMISTRY OF FARM PRACTICE 

is composed always of the same elements combined in 
the same proportion by weight. A compound possesses 
properties which differ from those of the elements of which 
it is composed. Chemists have recognized many thousands 
of compounds, each of which has a characteristic set of 
properties which is constant and differs from that of other 
compounds. 

The element carbon, a black solid, will combine chem- 
ically under certain circumstances with the jtIIow solid, 
sulphur, and form a compound, carbon disulphide, which 
is a transparent liquid with a characteristic odor, and 
very volatile at ordinary temperatures. The formation 
of compounds is due to the chemical attraction existing 
between the atoms of the elements which causes them 
. to combine to form the molecules of the compound. 

15. Mixtures. Two or more substances may be ever 
so intimately blended together, but, if no chemical com- 
bination takes place, there is no compound produced. 
Such a mingling is termed a mixture. A mixture differs 
from a compound in two ways: First, it possesses the 
characteristic properties of all of its ingredients; second, 
the proportion of its constituents may vary each time 
the mixture is made. In this respect a mixture differs 
from a compound in which the percentage content of its 
constituents does not vary. 

16. Valence. When hydrogen gas is mixed with chlorine 
gas and exposed to diffused light, it is found that hydrogen 
chloride, a compound whose molecules consist of one atom 
of each element, is produced. While the reason for the 
affinity between atoms of hydrogen and of chlorine is not 
known, yet there is some kind of attraction, possibly elec- 
trical, which draws and binds these atoms together. We 
may imagine that each hydrogen atom has a string attached 
to it by means of which it unites itself to other atoms. The 
hydrogen atom seems to have but one of these strings 
which may be called bonds or valences, and it is there- 



COMPOUNDS— MIXTURES— VALENCE, ETC. 15 

fore called a monad, or univalent element. The chlorine 
atom usually acts as a monad and we may picture that, 
when hydrogen chloride is produced, the bond of a chlorine 
atom ties itself to the bond of a hydrogen atom, thereby 
making a stable molecule. One atom of chlorine will 
combine with one atom of potassium to form a molecule 
of potassium chloride. The potassium atom is therefore 
univalent. 

The atoms of some elements have the capacity to hold 
in combination two atoms of a univalent element. We 
may think of such elements as having two bonds attached 
to each atom; two atoms of hydrogen are required to unite 
to one atom of oxygen so as to form water, therefore, the 
valence of oxygen is two. Oxygen is called a diacl or 
bivalent element. A number of important elements are 
bivalent, such as calcium, magnesium, and zinc. One 
atom of nitrogen unites with three atoms of hydrogen to 
form ammonia. Therefore nitrogen in this case is a triad 
or trivalent element. Other elements usually trivalent are 
phosphorus and aluminium. Carbon as indicated by the 
four atoms of hydrogen, which unite with one atom of 
carbon to form marsh gas, is tetravalent. 

Sometimes an element may develop one valence under 
one set of conditions and a different valence under other 
conditions. Hydrogen never changes valence, oxygen prac- 
tically never, and the same is true of some of the metallic 
elements, such as calcium, sodium, and potassium. When 
oxygen combines with an element it is liable to develop 
in that element an increase in its valence. For example, 
when sulphur unites with hydrogen to produce the ill- 
smelling gas, hydrogen sulphide, the valence of the sul- 
phur atom is two, as indicated by the two atoms of hydrogen 
which it requires. When sulphur is burned in air, most 
of the resulting compound is sulphur dioxide, the two oxygen 
atoms of the compound indicating that sulphur has four 
bonds; in this action a small amount of sulphur trioxide 



16 CHEMISTRY OF FARM PRACTICE 

is produced and this compound with its three oxygen 
atoms shows that the sulphur atom develops six bonds. 
In the table of elements given on page 6 the usual valence 
of each element is given. The theory of valence is used 
with advantage in fixing in the mind the formulas of com- 
pounds. 

17. Formulas. The attraction existing between atoms 
binds them into molecules. These may be represented by 
formulas which are made up of a combination of symbols. 
The formula HC1 denotes one atom of hydrogen chemically 
combined with one atom of chlorine. It also indicates a 
weight of hydrogen chloride equal to the combined weight 
of its atoms. This is the molecular weight and is equal 
to 1+35.46 or 36.46. Two molecules of hydrogen chloride 
are expressed 2HC1. The molecule of water is expressed by 
the formula H2O, indicating two atoms of hydrogen united 
with one atom of oxygen. A molecule of sulphuric acid 
is H2SO4. This indicates that it is composed of two atoms 
of hydrogen, one of sulphur, and four of oxygen. Three 
molecules of sulphuric acid would be expressed by the 
term 3H2SO4. In this latter formula there are in all six 
atoms of hydrogen, three of sulphur, and twelve of oxygen. 
The formula 2Ca3(P04)2 means two molecules of calcium 
phosphate. The two molecules contain six atoms of cal- 
cium, four atoms of phosphorus, and sixteen atoms of 
oxygen. It will be seen that each of the coefficients 
3 and 2 in these two examples multiplies each of the sym- 
bols following it, taken as many times as is indicated by 
the subscript following each symbol. Each of the symbols 
within the parenthesis is in turn multiplied by the sub- 
script following the parenthesis. 

18. Hydrates. Many salts are loosely combined with 
water to form hydrates; thus, when copper sulphate is 
dissolved in water and the water is slowly evaporated there 
will form blue crystals which contain five hydrating mole- 
cules, and this formula of the resulting blue vitriol is written 



COMPOUNDS— MIXTURES— VALENCE, ETC. 17 

CuS04-5H 2 0. Likewise, the formula of gypsum, or hy- 
drated calcium sulphate, may be written CaS0 4 -2H 2 0. 
When this is heated, it loses three-fourths of its water, 
and the resulting plaster of Paris has the formula 
(CaS0 4 ) 2 -H 2 0. 

The number of bonds which each component part of 
a compound possesses determines its formula. Thus, in 
sodium chloride, sodium and chlorine each have one bond, 
and therefore the formula is NaCl. In sodium sulphide, 
the sulphur atom has two bonds, and therefore requires 
two sodium atoms, each with its one bond, to satisfy it; 
consequently the formula is Na 2 S. In arsenious oxide, it 
requires two arsenic atoms, each with three bonds or six 
together, and three oxygen atoms, each with two bonds, 
to make the formula, As 2 03, in which the total bonds of 
the arsenic atoms shall equal the total bonds of the oxy- 
gen atoms. In some conditions, arsenic develops five bonds, 
and consequently the formula of arsenic oxide is AS2O5. 

19. Criss-cross Rule. In compounds which are com- 
posed of two units, the formula may be determined by 
taking as many atoms or parts of one component as there 
are bonds of the other component. This is more apparent, 
if, first, the bonds of each part are indicated. Thus, in 
determining the formula of aluminium oxide, write the 
symbols and indicate the bonds of each, A1'"0", then, 
applying the " criss-cross " rule, the formula becomes 
AI9O3. In the formula for copper sulphide the bonds 
would be Cu"S", and the formula, Cu 2 S 2 ; but it is cus- 
tomary to reduce such formulas to their lowest terms, which 
in this case will be CuS. 

In formulas having more than two components, very 
frequently two or more of the elements group themselves 
together and act as a unit. Such groups do not generally 
separate when they take part in a chemical reaction. They 
are termed radicals. Thus, in the formula of phosphoric 
acid, H3PO4, the PO4 acts as a radical, and in the formula 



18 CHEMISTRY OF FARM PRACTICE 

for ammonium carbonate (NH^COs, the NH4 and the 
CO3 are each radicals. Radicals may be considered as 
having free bonds, the same as elements. In H3PO4 the 
PO4 has three bonds. This is indicated by the fact 
that it requires three monovalent hydrogen atoms to sat- 
urate it. 

In acids the portion after subtracting the acid hydrogen 
is a radical, and its bonds are indicated by the number of 
acid hydrogens subtracted, in salts the portion transferred 
from the acid from which it was derived is a radical with 
the same number of bonds as in the acid. In bases, the 
hydroxyl, OH, is a radical, each hydroxyl having one free 
bond. 

By following these directions, the formulas of the com- 
mon compounds may be written, provided the bonds of 
the elements and the formulas of the acids are in mind. 
On the other hand, the bonds of elements and radicals 
may be inferred if the formulas of compounds are known. 

The formula of the salt, calcium silicate, may be de- 
rived as follows: This silicate salt is related to silicic acid. 
Silicic acid has the formula H4Si04. Its acid radical is 
Si04, which has four bonds, as shown by the four hydrogen 
atoms. Calcium is a bivalent radical. This could be 
inferred if a formula of any common substance containing 
calcium is known, e.g., CaCl2 or Ca(OH)2. Chlorine, we 
know, has one bond, and applying the criss-cross rule, we 
have Ca^CV, therefore, calcium is bivalent. Now, writing 
for calcium silicate, CaSi04, and inserting the marks for 
the bonds, Ca"(Si04)"", and applying the criss-cross rule. 
Ca4(Si04)2, and reducing to its lowest terms, we have the 
correct formula CaoSi04. 

We may derive the formula for aluminium sulphate in 
a similar way. A sulpha te is related to sulphun'c acid, 
H2SO4. The acid radical SO4 has two bonds, because of 
its two hydrogen atoms. Aluminium has three bonds, as 
indicated by the formula for its oxide, AV'Os". So, 



COMPOUNDS— MIXTURES— VALENCE, ETC. 19 

inserting the bonds, we have A1 /// (S04) // , and applying 
the rule, the correct formula would be Al2(S04)3- 

20. Equations. Chemical reactions are expressed by 
equations which show in a condensed form the kind and 
the quantities both of the substances entering into the 
reaction and of the products formed. Equations may be 
placed in four classes: 

(1) Combination. When two or more substances unite 
to form a new combination, as, by example, 

Fe+S = FeS. 

This equation is read, one atom of iron unites with 
one atom of sulphur to produce one molecule of iron sul- 
phide. 

It also indicates that one atomic weight of iron, 56, 
is uniting with one atomic weight of sulphur, 32, and pro- 
ducing a molecular weight of iron sulphide, 88. 

H 2 +0 = H 2 0. 

This may be translated, one molecule of hydrogen 
weighing 2, unites with one atom of oxygen weighing 16, 
and produces one molecule of water weighing 18. 

(2) Decomposition. When a substance is separated into 
two or more substances, the analysis may be expressed 
as follows: 

H 2 C03 = H 2 0+C02. 

This may be read, one molecule of carbonic acid, weight 
62, is decomposed into one molecule of water, weight 18, 
and one molecule of carbon dioxide, weight 44. 

Fe 2 3 = 2Fe+30. 

One molecule of ferric oxide yields two atoms of iron 
and three atoms of oxygen. 

It is known that oxygen in a free condition exists as 
molecules of two atoms each. The number of atoms in 



20 CHEMISTRY OF FARM PRACTICE 

a molecule of metallic iron has not been determined. There- 
fore, by doubling the equation above, it may be so written 
as to meet these conditions. 

2Fe 2 3 = 4Fe+30 2 . 

This is read, two molecules of ferric oxide will produce 
four atoms of iron and three molecules of oxygen. 

(3) Substitution. Frequently an element may be sub- 
stituted for a portion of a compound, provided it is chem- 
ically equivalent to the displaced portion. 

Mg+2HCl = MgCl 2 +H 2 . 

One atom of bivalent magnesium here substitutes for 
two atoms of monovalent hydrogen. 

The formula for water, H2O, may be written HOH, 
in which OH is a radical. Metals such as sodium react 
with water as shown by the substitution equation. 

Na+HOH = H+NaOH. 

This equation doubled, 

2Na + 2HOH = H 2 + 2NaOH, 

would be read, two atoms of sodium plus two molecules 
of water will produce one molecule of hydrogen and two 
molecules of sodium hydroxide. 

When iron is exposed to steam the reaction would be 
expressed, 

Fe+3HOH = Fe(OH) 3 +3H, 
or better, 

2Fe+6HOH = 2Fe(OH) 3 +3H 2 . 

(4) Double Decomposition. When acids or bases or 
salts react with one another, there is a simple exchange 
between the parts of the decomposing substances. This 
is the most common sort of chemical equation. 



COMPOUNDS— MIXTURES— VALENCE, ETC. 21 

In writing such equations, first indicate this change. 
Thus, in the case of the reaction between nitric acid and 
copper hydroxide, 

HN0 3 +Cu(OH) = CuN0 3 +HOH. 

Then indicate the bonds of the different radicals and ele- 
ments 

H(N0 3 ) , +Cu ,/ (OH) , = Cu ,, (N0 3 )'+H ,, (OH)'. 

Next correct the formulas by noting the bonds and em- 
ploying the criss-cross rule, 

HN0 3 + Cu(OH) 2 = Cu(N0 3 ) 2 +HOH. 

Select one of the more complicated formulas, such as 
Cu(N0 3 ) 2 , and check off its parts to see if an equal number 
of such parts appear on the other side of the equation. 
Note that it has two (N0 3 ) radicals, which, to balance the 
equation, must appear in the left-hand, or factor side of 
the equation: so take 2HN0 3 . Likewise note the two OH 
of Cu(OH) 2 , and provide for their appearance on the 
right or product side of the equation, i.e., 2HOH. The 
equation now becomes, 

2HN0 3 +Cu(OH) 2 = Cu(N0 3 ) 2 +2HOH. 

Finally, check off each element or radical and see that it 
appears an equal number of times on each side of the 
equation. The equation then balances and will be correct. 

In a similar manner, the equation expressing the reac- 
tion between the two salts, antimony sulphide and sulphuric 
acid may be balanced. 

SbS+H 2 S0 4 =SbS0 4 +H 2 S (exchanging radicals), 
Sb"'S"+H 2 S0 4 = Sb'"(S0 4 )"+H'S" (indicating bonds), 
Sb 2 S 3 + H 2 S0 4 =Sb 2 (S0 4 ) 3 +H 2 S (correcting formulas), 
Sb 2 S 3 +3H 2 S0 4 =Sb 2 (S0 4 ) 3 +3H 2 S (balancing and checking 
off). 



22 CHEMISTRY OF FARM PRACTICE 

In the reaction between phosphoric acid, H3PO4, and 
sodium hydroxide, NaOH, if there were present enough of 
the base to replace one only of the three acid hydrogens, 
we could represent the action by the equation, 

I NaOH+H 3 P04 = NaH 2 P0 4 +H 2 0. 

In the formula of the sodium dihydrogen phosphate, it 
will be noticed that the three bonds of the acid radical, 
PO4, are held by a combination of three bonds, one from 
the sodium atom and two from the two hydrogen atoms. 

Should there be sufficient sodium hydroxide to replace 
two of the three hydrogen atoms of phosphoric acid, the 
trial equation would be, 

NaOH+H 3 P0 4 = Na 2 HP0 4 +H 2 0. 

it will be seen that the total number of sodium, oxygen, 
or hydrogen atoms on one side of the equation does not 
correspond or balance the atoms of these elements on the 
other side. Starting with the disodium hydrogen phos- 
phate, which is the most complicated formula of the equa- 
tion, its two sodium atoms require two sodium atoms in 
the left-hand or factor side of the equation, therefore, we 
take two molecules of sodium hydroxide. The equation 
then will be balanced, except its hydrogen and oxygen, 
which may be made equal on each side by making two 
molecules of water on the product side. 

II. 2NaOH+H 3 P0 4 = Na 2 HP0 4 +2H 2 0. 

When there is excess of sodium hydroxide, Na 3 P(>4, would 
be formed and the equation would be, 

III. 3NaOH + H 3 P0 4 = Na 3 P0 4 + 3H 2 0. 

Thus we find three different reactions represented by the 
three equations which are possible when sodium hydroxide 
is treated with phosphoric acid. 



COMPOUNDS— MIXTURES— VALENCE, ETC. 23 

Calcium phosphate, Cas'^PC^V, is used as a source 
of fertilizer. As it is very insoluble in water, in order to 
make it soluble and thereby quickly available as a plant 
food, it is treated with sulphuric acid, which changes the 
phosphate into a more soluble form. The following reac- 
tions may take place: 

I. Ca 3 (P0 4 ) 2 + 3H2SO4 = 2H3PO4 + 3CaS0 4 , 
II. Ca 3 (P04)2+2H2S04 = CaH 4 (P0 4 )2+2CaS04 J 
III. Ca 3 (P04)2+H 2 S04 = 2CaH(P0 4 ) +CaS0 4 . 

These equations should be read and the balancing of them 
checked. 



CHAPTER III 

ACIDS— BASES— SALTS— ANHYDRIDES— DISSOCIATION- 
NOMENCLATURE 

21. Groups of Elements. The chemical elements may 
be roughly divided into three large groups: 

(1) Metals. These are base-forming elements. There 
are somewhat more than a dozen of these elements that 
are important. 

(2) Non-metals. These are acid-formers. The common 
acid-forming elements are oxygen, sulphur, nitrogen, carbon, 
silicon, boron, phosphorus, fluorine, chlorine, bromine, and 
iodine. 

(3) Metalloids. Between the two groups (1) and (2) 
are a few intermediate elements which act either as acidic 
or basic, according as they are influenced by combination, 
on the one hand with strong basic elements, or on the 
other hand with strong acidic elements. These border-line 
elements thus are seen to be rather indifferent in their 
chemical affinities. The common metalloids are chromium, 
aluminium, manganese, arsenic, antimony, and tin. 

22. Classes of Compounds. Most of the compounds of 
inorganic chemistry are included in one of the four classes — 
acids, bases, salts, and anhydrides. The properties and 
the composition of each of these classes must be studied 
carefully in order to gain a working knowledge of chemistry. 

23. Acids. The most important acids are sulphuric, 
H2SO4; hydrochloric, HC1; nitric, HNO3; phosphoric, 
H3PO4; and acetic, HC2H3O2. If these or the score of 
other commonly-occurring acids should be examined, they 
all will be found to have the following characteristic prop- 
erties : 

24 



ACIDS— BASES— SALTS— ANHYDRIDES, ETC. 25 

(a) They are sour to the taste. 

(b) They have the power of turning to a pink color 
paper that has been stained blue by an organic dye com- 
monly called litmus. 

(c) When in water solution, they attack such metals 
as zinc and magnesium, thereby being themselves broken 
up into hydrogen or some compound of hydrogen, as one 
of the decomposition products. Most frequently, this action 
may be observed by the bubbles of effervescing gas rising 
through the liquid acid solution. 

(d) They are soluble in water. They differ, however, 
in degree of solubility, 

(e) They contain hydrogen, which is easily separated 
from the remainder of the acid when it acts chemically 
upon other substances. 

(/) Acids react with bases, thereby neutralizing or de- 
stroying the characteristic properties of both acid and 
base. 

(g) In respect to their composition, acids may be divided 
into two classes: 

(1) The Oxygen Acids. These are composed of hydrogen 
which is bound by means of oxygen to a non-metallic ele- 
ment or radical. For example, hypochlorous acid, HCIO, 
may be considered as H — O — CI; nitric acid as H — O — NO^; 

H— 0\ 

sulphuric acid as >S(>2. 

H— (K 

(2) Hydrogen Acids. These do not contain oxygen. 
The formula of the six common hydrogen acids are HC1, 
HBr, HF, HI, H 2 S, HCN. 

24. Bases. Some of the most common bases are sodium 
hydroxide, NaOH; potassium hydroxide, KOH; ammo- 
nium hydroxide, NH 4 OH; calcium hydroxide, Ca(OH) 2 ; 
barium hydroxide, Ba(OH)2. Bases have, generally, prop- 
erties the opposite of those exhibited by acids. 

(a) Bases that are soluble in water have an alkaline 
taste and feel soapy to the touch. 



26 CHEMISTRY OF FARM PRACTICE 

(6) When in water solution, bases turn back to a blue 
color litmus paper that has been made pink by the action 
of an acid. 

(c) The stronger bases attack metals such as aluminium 
and zinc, producing thereby water as one of the products 
of the reaction. 

(d) Generally they are insoluble in water. Those enu- 
merated above are the only ones that will dissolve appre- 
ciably in water. The three first mentioned above are 
very soluble and are called the alkalies. 

(e) Bases all contain the radical, hydroxyl, OH, the 
only other constituent being a metal. This hydroxyl is 
easily separated from the metal. 

(/) Bases react easily with acids, the hydroxyl of the 
base uniting with the hydrogen of the acid, producing 
thereby water (OH + H = H 2 0). This action takes away 
or neutralizes the characteristic properties of both acids 
and base. 

(g) Bases are composed of a metal bound by means of 
oxygen to hydrogen. For example: silver hydroxide, 
AgOH; mercurous hydroxide, HgOH; copper hydroxide, 
Cu(OH) 2 ; iron hydroxide, Fe(OH) 3 . 

25. Salts. Salts have no characteristic properties de- 
fining them as a class. They may be best described by 
their methods of production and by their composition. 

(a) When the acid hydrogen of an acid is replaced by 
a metal, the resulting compound is a salt. For example: 
Replacing the two hydrogens of sulphuric acid, H2SO4, 
by the bivalent metal zinc, a salt, zinc sulphate, ZnSCU, 
is produced; replacing the hydrogen of nitric acid, HNO3, 
by the univalent metal silver, a salt, silver nitrate, AgN03, 
is produced. 

(b) When the hydroxyl of a base is replaced by a non- 
metal or by a non-metallic radical, the resulting com- 
pound is a salt. For example: When the hydroxyls of 
the base, zinc hydroxide, Zn(OH)o, are replaced by the 



ACIDS— BASES— SALTS— ANHYDRIDES, ETC. 27 

non-metallic or acid radical, SO4, the result will be the 
salt, zinc sulphate, ZnSCU; replacing the hydroxyl of 
sodium hydroxide by the non-metallic element, chlorine, 
the result will be a salt, sodium chloride, NaCl. 

(c) When acids and bases react with each other, water 
is always produced by the union of the hydrogen of the 
acid with the hydroxyl of the base, H+OH = H20. What 
is left of the acid after its hydrogen is removed is the acid 
radical. For example: NO3 from nitric acid, HNO3. 
What is left of the base after its hydroxyl is removed is 
the metal: For example, K from the base potassium hy- 
droxide, KOH. These remnants will unite and thereby 
form a salt; K and NO3 produce the salt potassium nitrate, 
KNO3. 

There are four classes of salts: 

(1) Normal Salts. These contain only the metal and 
the acid radical, such as sodium nitrate, NaN(>3, or potas- 
sium phosphate, K3PO4. They may be regarded as the 
salts in which all the hydrogen of the acid has been replaced 
by a metal. 

(2) Acid Salts, In these one or more of the hydrogens 
of the acid from which the salt is derived has been re- 
tained. For example: sodium hydrogen sulphate, NaHS(>4, 
potassium hydrogen phosphate, KHSO4. These generally 
are able to turn blue litmus to a pink^color on account of 
the acid hydrogen left in them. 

(3) Basic Salts. In these, some of the hydroxyl of 
the base from which the salt was derived has been retained. 
For example, basic bismuth nitrate, Bi(OH)2N03. This is 
produced by substituting the acid radical NO3 for one 
of the hydroxides of the base, Bi(OH)3. 

(4) Neutral Salts. These salts, when in water solu- 
tion, do not change color in either blue or pink litmus 
paper. 

26. Anhydrides. This word means without water. An- 
hydrides may be considered as either acids or bases from 



28 CHEMISTRY OF FARM PRACTICE 

which water has been subtracted. They are quite gen- 
erally oxides, that is, compounds in which oxygen is com- 
bined with one other element. There are two classes: 

(1) Acid Anhydrides. For example: Sulphuric anhy- 
dride, SO3, produced by subtracting water, H 2 0, from 
sulphuric acid, H2SO4; nitric anhydride, N 2 5 , produced by 
subtracting water from two molecules of nitric acid, HNO3. 

(2) Basic Anhydrides. For example: Calcium oxide, 
CaO, produced by subtracting water from the base, cal- 
cium hydroxide, Ca(OH) 2 ; sodium oxide, Na 2 0, produced 
by subtracting water from two molecules of the base NaOH. 

27. Dissociation. If an acid or a base or a salt is dis- 
solved in water and a current of electricity is passed through 
the solution, it will be found that the compound will tend 
to separate into two parts, one of which will accumulate 
at the + electrode, where the current enters the solution, 
while the other portion will condense about the — elec- 
trode, where the current leaves the solution. As opposite 
kinds of electric charges attract each the other, the portion 
attracted to the + electrode is called the electro-negative 
part of the compound, and the portion attracted towards 
the — electrode is called the electro-positive portion of the 
compound. These portions, because they move through the 
solution, are termed ions. In the case of acids it is found 
that the replaceable or acid hydrogen of the acid is con- 
densed about the — electrode, and is therefore electro- 
positive, while the remainder of the acid, the acid radical 
portion, moves toward the + electrode and is therefore 
electro-negative. These are some examples: 
+ - + - + 
HC1, FI(N0 3 ), H(C 2 H 3 2 ). 

When salts are thus electrolyzed, the metallic part of 
the salt is found to be electro-positive, and the acid radical 
part is electro-negative : 

+ -+-+- + - + 

ZnCl 2 , PbS, Na 3 (P0 4 ), Na(H 2 P0 4 ), Na 2 (HP0 4 ). 



ACIDS— BASES— SALTS— ANHYDRIDES, ETC. 29 

In the case of bases the metallic portion is electro- 
positive and the hydroxyl is electro-negative. This is 
indicated in the following formulas of bases: 

+ - + - + - 

Na(OH), Ca(OH) 2 , Fe(OH) 3 . 

There are reasons for believing that when acids or bases 
or salts are dissolved in water, even when no electric cur- 
rent is passing through the solution, the compounds to 
some extent break up, or, as it is termed, dissociate into 
ions highly charged either positively or negatively. The 
ions with electro-negative charges are acid-forming. They 
are either the non-metallic elements or are radicals con- 
taining non-metals. According to the dissociation theory, 
acids are electro-negative elements or radicals united to 
hydrogen, and bases are electro-positive elements united 
to hydroxyl (OH), and salts are electro-positive elements 
united to electro-negative elements or radicals, 

28. Nomenclature of Compounds. Names are given 
to most chemical compounds according to a few simple 
rules. 

(1) Nomenclature of Binary Compounds, (a) Compounds 
composed of two elements have names ending in ide. This 
affix is attached to the abbreviated name of the non- 
metallic part of the compound. Thus oxygen forms oxides, 
as calcium oxide, CaO; sulphur forms sulphides, as lead 
sulphide, PbS; chlorine forms chlorides, as sodium chloride, 
NaCl. To indicate the number of atoms of the non- 
metallic element in the compounds, the prefixes mono for 
one, di, for two, tri for three, and tetra for four, are used; 
thus CO is carbon monoxide; SO2 is sulphur dioxide; ASCI3 
is arsenious trichloride; CCU is carbon tetrachloride. 

(b) In case two compounds are made by the same two 
elements entering into combination in varying propor- 
tion, the name of the metallic element is modified by the 
terminations ous or ic. Thus HgCl is called mercurcws 



30 CHEMISTRY OF FARM PRACTICE 

chloride, and HgCk is called mercunc chloride. The 
compound in which there is the larger ratio of non-metallic 
component assumes the termination ic, while the com- 
pound having the smaller proportion of the non-metallic 
component has the termination ous. For example: FeO 
is ferrous oxide; Fe2C>3 is feme oxide; SnS is stannous 
sulphide; SnS 2 is stanmc sulphide. 

(2) Nomenclature of Acids. The name of the acid- 
forming element to which is added the affix ic is assigned 
to the most common acid formed by that element: Thus 
sulphuric acid, H2SO4; phosphoric acid, H3PO4; chloric 
acid, HCIO3. When the elements form an acid which 
contains a larger amount of oxygen, the prefix per is used, 
as persulphuric acid, H2S4O8. In case the element forms 
an acid containing less oxygen than its ic acid, the termina- 
tion ous is used, as sulphurous acid, H2SO3. An acid with 
still less oxygen is designated by the prefix hypo as well as 
the affix ous; as H2SO2, %posulphurous acid. 

(3) Nomenclature of Salts. Names of those salts which 
contain more than two elements are determined from the 
names of the acids from which they are derived. Here 
are the two important cases: 

The names of salts end in ate which are derived from acids 
ending in ic. 

The names of salts end in ite which are derived from 
acids ending in ous. 

Examples: 

Sodium sulphate, Na 2 S04, formed from sulphuric acid, 
H 2 S0 4 . 

Silver nitrate, AgNC>3, formed from nitn'c acid, HNO3. 

Sodium sulphite, Na 2 S03, formed from sulphurous acid, 

H 2 S0 3 . 

Sodium hyposulphite, Na 2 S0 2 , formed from hyposul- 
phurous acid, H2SO2. 

The following illustrate the series of chlorine acids 
and the salts derived from them: 



ACIDS— BASES— SALTS— ANHYDRIDES, ETC. 31 

HCIO4, perchloric acid: KC10 4 , potassium perchlorate. 

HCIO3, chloric acid: KCIO3, potassium chloral. 

HCIO2, chlorous acid: KCIO2, potassium chlorzte. 

HCIO, hypochlorous acid : KCIO, potassium hypochlorite. 

Salts derived from the hydrogen acids, such as HC1, 
HBr, H 2 S, contain but two elements and follow the rule 
in 1 (a) rather than that of 3; thus CaCl2, from hydrochloric 
acid, is not called calcium hydrochlorate, but is termed 
calcium chloride. 



CHAPTER IV 

THE ELEMENTS NECESSARY FOR PLANT GROWTH- 
OXYGEN— HYDROGEN— CARBON— NITROGEN— PHOS- 
PHORUS— SULPHUR— POTASSIUM— CALCIUM— MAGNE- 
SIUM— IRON 

29. Oxygen. Oxygen is the most abundant of the ele- 
ments. Upon it the life of plants as well as of animals 
directly depends. The greater part of the energy mani- 
festing itself in the motion of objects about us is the result 
of the chemical activity of oxygen. Power for the pur- 
poses of commerce, energy which drives electric and steam 
cars, and the heat necessary for the sustenance of life 
and the maintenance of a temperature which makes life 
possible in other than tropical countries, all are derived 
from heat produced when oxygen combines with com- 
bustible substances. 

Occurrence. In a free condition oxygen exists in vast 
quantities in the atmosphere, of which it is nearly 21 per 
cent by volume. In combination with other elements it 
is found in thousands of different compounds. Nearly 
nine-tenths of water is oxygen. It forms nearly one-half 
of the rocks composing the crust of the earth. It is rather 
difficult to find, in any of the common objects about us, 
a substance that is not combined with oxygen. Other 
than those substances that have been artificially produced 
by man and those that like carbon in coal are the product 
of vegetable life, almost the entire earth is composed of 
oxygen compounds. 

Properties. When free, oxygen is an odorless gas 
without color or taste. It is a little heavier than air and 
is soluble in water at ordinary temperature to the extent 

32 



ELEMENTS NECESSARY FOR PLANT GROWTH 33 

of three volumes of the gas to one hundred volumes of the 
liquid. Fish and other marine life are dependent upon 
this oxygen dissolved in the water. With very few excep- 
tions oxygen forms compounds with all the other ele- 
ments; in this respect no other element can compare with 
oxygen. 

The activity of oxygen in forming chemical combina- 
tion is remarkably increased by raising its temperature. 
Many substances that resist any except very slow oxidation, 




Fig. 6. — Preparation of oxygen in the laboratory. 

when heated in the air, will unite with oxygen so rapidly 
that they suffer combustion. This is remarkably apparent 
when a building in conflagration is entirely consumed in 
a short time. Oxygen is absolutely essential in the build- 
ing up of plant tissues. The carbohydrates, the proteids, 
and the fats, the constituents of plants that give to them 
their value as foods, are composed in large part of oxygen. 

In the process of decay and in the disposal of sewage, 
oxygen plays a beneficial role, decomposing germs that, 
if allowed to multiply, would produce epidemic diseases. 



M CHEMISTRY OF FARM PRACTICE 

Preparation. Although oxygen exists at hand in enor- 
mous quantities in a free condition in the air, yet it is 
easier to obtain it by decomposing some of its compounds 
than to try to separate it from the nitrogen with which 
it is mixed in the atmosphere. In the chemical laboratory 
it may be produced by heating in a test-tube a little of the 
white salt, potassium chlorate (KCIO3). This melts at 
a comparatively low temperature (360° C.) and soon begins 
to boil, yielding an abundant supply of oxygen. This 
decomposition takes place at a still lower temperature 
(200° C.) when the black mineral, pyrolusite (manganese 
dioxide) is mixed with the potassium chlorate in the pro- 
portion of three parts of the chlorate to one part of the 
pyrolusite. The method of producing and of collecting 
the gas is shown in Fig. 6. 

30. Hydrogen. The element hydrogen is a colorless 
gas. Very little is found in a free condition, although a 
small amount, estimated as one part in thirty thousand, 
exists in the air. It is not so active chemically as oxygen, 
forming compounds with comparatively few of the other 
elements. 

Occurrence. Some of the compounds of hydrogen are 
of great importance. The principal source of hydrogen is 
water, of which it constitutes about 11 per cent. It is an 
essential ingredient of animal and plant structure. Organic 
substances, such as starch, sugar, albumen, and fat; bodies 
formed from organic matter, such as petroleum oil, bitu- 
minous coal, and coal tar, and the vast number of hydro- 
carbons, such as marsh gas, and acetylene, and the alcohols, 
all are made in part of hydrogen. All acids and all bases 
contain hydrogen as an essential ingredient, Ammonia 
and its compounds, which form an important food for 
plants, contain hydrogen. 

Preparation. Hydrogen, as well as oxygen, may be 
obtained by the electrolysis resulting when an electric 
current is passed through water. In order that the elec- 



ELEMENTS NECESSARY FOE. PLANT GROWTH 35 



Oxygen - 




Hydrogen 



trie current may pass through, the water is first mixed 
with a little sulphuric acid. The gases are most easily 
collected by means of an apparatus shown in Fig. 7. The 
volume of the hydrogen evolved is twice that of the oxygen. 

Properties. Hydrogen will burn in air with a blue 
flame, yielding a quantity of 
heat greater than that pro- 
duced by the combustion of 
the same weight of any other 
combustible. A quarter of a 
ton of hydrogen when burned 
will furnish as much heat as 
can be obtained from a ton 
of coal. For this reason coal 
gas, which is composed of 
about 50 per cent of hydrogen, 
is an economical fuel for cook- 
ing purposes. 

Hydrogen is the lightest 
known substance. Air is nearly 
14J times as heavy as hy- FlG> 7 ._Electrolysis of water, 
drogen gas, hence the latter 

is used for inflating balloons and for dirigibles. Hydrogen 
is a product of the decay of many organic bodies. When 
burned in air, it unites with oxygen and produces steam 
according to the equation 

H 2 +0=H 2 0. 

31. Carbon. Next to oxygen carbon enters most 
abundantly into the composition of plants. It is a very 
important element, although not nearly so widely distrib- 
uted as oxygen. It exists in the air in the form of the 
compound carbon dioxide gas, CO2, constituting nearly 
four parts in ten thousand parts of air. Carbon exists 
in the soil as the carbonates of certain metallic elements 
such as calcium and magnesium. The diamond is a crys- 




36 



CHEMISTRY OF FARM PRACTICE 



tallized form of carbon. Most of anthracite, bituminous 
coal, and charcoal is carbon. Graphite is almost pure 
carbon. 

The three compounds of carbon that interest us most 
from an agricultural view-point are carbon dioxide, the 
carbonates, and the carbohydrates. The soil water con- 
tains a certain amount of carbon dioxide, which is produced 
through the decay of organic matter in the earth. The 
higher the per cent of carbon dioxide in the water, the 
greater will be its solvent power. Thus, water percolating 




OJPPER EPIDERMIS LOWER EPIDERMIS CROSS SECTION 

Fig. 8. — Structure of a leaf. The stomata are shown in the lower 
epidermis and in the cross-section. 



through the soil and absorbing carbon dioxide will dissolve 
mineral matter and become hard water. 

The carbonates are compounds of carbon dioxide and 
a basic anhydride. Thus, CaO+C02 = CaC03. Carbon- 
ate of lime, CaC03, is agriculturally the most important of 
the carbonates. The carbohydrates contain carbon and 
hydrogen and oxygen, the latter two being in the pro- 
portion of water, H2O. The carbohydrates are formed 
in plants by the condensation of formic aldehyde. Formic 
aldehyde is formed in the green part of plants in the presence 
of sunlight, by the union of carbon dioxide, which enters 
through the stomata or breathing pores of the leaf of the 



ELEMENTS NECESSARY FOR PLANT GROWTH 37 

plant, with water. During this process, oxygen is given 
off from the plant. 

32. Nitrogen. When pure, nitrogen is a colorless, 




FlG 9 —Roots of red clover showing nodules by which nitrogen is 
secured for the plant. 



odorless, tasteless and very inactive gas. It combines 
directly with but few elements, although indirectly it enters 
into the formation of a large number of compounds possess- 



38 CHEMISTRY OF FARM PRACTICE^ 

ing very marked properties. Nitrogen, in the free state, 
forms about four-fifths by volume of the atmosphere; 
it exists in combination with other elements in important 
compounds, such as ammonium hydroxide (NH 4 OH), one 
of the alkali bases; in nitric acid (HNO3), one of the strongest 
acids; and in the ammonium form (NH4), as a salt of many 
acids. It is present in combination in animal and in plant 
tissues. Nitrogen is available as plant or animal food 
only when it enters into some combination. It is the most 
expensive and at the same time the most elusive element 
with which the farmer has to deal. 

While four-fifths, by volume, of the atmosphere is 
nitrogen, most plants are powerless to extract it from 
the air. A small amount of ammonia gas is formed in 
the atmosphere by electrical discharges and washed to 
the earth by rain water; in a similar way some of the 
oxides of nitrogen are formed. Certain bacteria that exist 
on decaying organic matter have the power of " fixing " 
atmospheric nitrogen in such combination that it will 
become available to the plants. A large amount of atmos- 
pheric nitrogen is " fixed " by means of bacteria that 
exist in so-called symbiotic union with leguminous plants. 
These bacteria form nodules on the roots of the plants 
which they infest, as shown in Fig. 9, the plants furnishing 
food for the bacteria, while the bacteria take nitrogen 
from the atmosphere and convert it into such a form that 
the plants can use it for the elaboration of their tissues. 
Peas, beans, vetches, clovers, alfalfa, peanuts, and beggar- 
weeds are examples of legumes. 

33. Phosphorus. Phosphorus is very easily oxidized, 
and, therefore, exists in nature in compounds only. It 
is quite widely distributed in combination with oxygen 
and calcium, as phosphate rock, which is largely calcium 
phosphate Ca3(PO.i)2. Phosphorus is often deficient in 
soils, and, as it is used rather plentifully for the develop- 
ment of both plants and animals, it is very often necessary 



ELEMENTS NECESSARY FOR PLANT GROWTH 39 

to make applications of it in a commercial form. It is a 
necessary constituent of the bones of animals, which are 
composed in part of calcium phosphate. Phosphorus has 
an important part to play in the formation of the seeds of 
plants and in hastening their maturity. When freshly 
prepared and kept in the dark, the element phosphorus is 
an almost colorless or slightly yellow, waxlike solid. It 
has a remarkably low kindling temperature, and therefore it 
is a very inflammable substance, and must be kept under 
water. Phosphorus appears luminous in the dark, due to 
its slow oxidation to phosphorous trioxide (P2O3) when 
in contact with moist air. Phosphorus fumes are very 
poisonous. When yellow phosphorus is heated to 240°-250° 
Centigrade, it is changed to the red or amorphous form, 
which has a much higher kindling temperature than the 
yellow form. When heated to 260° C, it is again changed 
to the yellow form. 

34. Sulphur. Sulphur occurs as yellow crystals, and 
also as opaque crystalline masses. It is found in nature 
in the free state, most frequently in volcanic regions. Com- 
pounds of sulphur with metals are known as sulphides; 
and when these compounds are more completely oxi- 
dized, they become sulphates. Compounds of sulphur are 
found widely distributed in both plants and animals. 
Small amounts of it occur in hair and in wool, while about 
1 per cent of it is present in the albuminous substances 
which are present to a large extent in both plants and 
animals. Sulphur is mined in large quantities in Louisiana, 
where the supply of the United States is produced. It 
is also produced in Sicily and Japan. Most of our soils 
contain sufficient sulphur for plant growth. 

35. Potassium. Potassium is rather abundant in nature, 
and especially so in soils that result from the decompo- 
sition of igneous rock. The minerals feldspar and mica 
contain potassium in large amounts. Granite rock con- 
tains over 3 per cent of potassium. Sea water contains 



40 



CHEMISTRY OF FARM PRACTICE 







a 



.a o 

*% 

03 .2 



2 -£3 



03 

bC 

C 

"2 



f 



ELEMENTS NECESSARY FOR PLANT GROWTH 41 

some potassium in the form of sulphates and chlorides. 
Potassium chloride occurs in deposits in the vicinity of 







a> o 



2 ^ 

c a, 
■9 ^ 

q fl 
►J .2 

If 

^ o 

Q3 

.g k 

O w 



3 
J3 

a 






Stassfurt, Germany, where it is mined in large quantities. 
Some seaweeds contain a small percentage of potassium; 



42 CHEMISTRY OF FARM PRACTICE 

wood ashes contain potash. Potassium has a tendency to 
lengthen the growing season of some crops. 

36. Calcium. Compounds of calcium are widely dis- 
tributed, but the element does not occur free in nature; 
it may be prepared by electrolysis. The most abundant 
compound of calcium is the carbonate. Calcium carbonate 
or " ground limestone rock " (CaC0 3 ) is of much agri- 
cultural importance, due to the fact that it corrects acidity 
in the soil. Calcium carbonate is a compound that is 
quite readily decomposed by other acids. Even the dilute 
acetic acid contained in vinegar will replace the carbonic 
acid of the calcium acetate. 

No plant growth can take place without the presence 
of calcium. It has been shown that even the rather insol- 
uble acid silicate of calcium may serve to furnish calcium 
to the plant. All normal soils have a supply of calcium 
compounds sufficient to furnish the calcium necessary for 
plant growth; but many soils are acid and, therefore, are 
benefited by applications of ground limestone to correct 
the acidity. These uses will be taken up later. 

37. Magnesium. Magnesium ranks a little below cal- 
cium in its abundance in nature. It, too, never occurs 
in the free state in nature. Its compounds are quite abun- 
dant in the earth's crust, in rocks, in sea water, and in 
mineral water. It is also widely distributed in both animal 
and vegetable life. It exists in nature largely in the car- 
bonate form, having the power to correct soil acidity, 
and being even more effective for this purpose per unit 
of weight than is calcium carbonate. If, however, mag- 
nesium is present in the soil in excess of about 1^ per cent, 
it produces undesirable effects on vegetation. 

38. Iron. Compounds of iron are widely distributed 
in nature in the form of brown or yellow oxides giving 
characteristic color to soils and as carbonate. These com- 
pounds form valuable deposits of iron ore. Iron sulphide 
in the form of pyrites or " fool's gold " is frequently found 



ELEMENTS NECESSARY FOR PLANT GROWTH 43 

in coal-bearing strata and in other rocks. The hydrated 
oxide is iron rust 

39. Summary. Of the ten elements necessary for plant 
growth, three — carbon, hydrogen, and oxygen — are exclu- 
sively derived from the atmosphere; one — nitrogen — 
partly from the atmosphere and partly from the soil; 
and six — phosphorus, potassium, sulphur, calcium, mag- 
nesium, and iron — are derived exclusively from the soil. 
From the standpoint of plant requirements only three are 
often deficient in soils — phosphorus, nitrogen, and potas- 
sium, and in many soils only one or two elements are de- 
ficient. The condition of the soil often warrants applica- 
tion of lime in some form. 



CHAPTER V 

WATER— SOLVENT ACTION OF WATER— DRINKING WA- 
TER—SPRINGS—SHALLOW WELLS— DEEP WELLS- 
TEMPORARY HARDNESS— PERMANENT HARDNESS- 
HOUSEHOLD WATER 

40. Properties of Water. The two gaseous elements, 
hydrogen and oxygen, have a strong chemical attraction 
each for the other. They unite whenever possible in the 
proportions of two volumes of hydrogen to one volume 
of oxygen, and, by weight, in the proportion of one unit 
of hydrogen to eight units of oxygen, to form water, which 
is one of the most stable of compounds. 

Water is possessed of remarkable physical and chemical 
properties. In common with most liquids, its volume 
changes with heating and cooling. When water is cooled, 
Hs maximum density is attained at the temperature of 
4° Centigrade. This temperature is still 4° above the 
freezing temperature of water. At a lower temperature 
than 4°, water again expands, and at zero, when it freezes, 
it again expands suddenly. This latter expansion accounts 
for the disintegrating effects of freezing, the force being 
so powerful that it will split large rocks, and it also accounts 
for the fact that ice will float. This remarkable abnormal 
expansion of water, when the temperature falls from 4° 
C. to 0° C.j results in the formation of ice at the surface 
of a cooing body rather than throughout its mass. When, 
by the radiation of heat into the air, the temperature at 
the surface of a body of water is cooled to 4° C, at which 
temperature it is densest, the cooled surface layers will 
continue to sink till the entire mass has reached the tem- 
perature of 4° C. Should the water grow still cooler, by 

44 



WATER— SOLVENT ACTION OF WATER, ETC. 45 

exposure to the cold air above it, it will now remain at 
the surface supported by the heavier, though warmer, 
water beneath, and, finally, when the surface water lowers 




to zero, it will freeze. Ice, being a solid lighter than water, 
will float upon it and being a poor conductor of heat will 
prevent further radiation from the water and prevent its 
freezing more than to a limited extent. Were it not for 
this rather miraculous provision of nature, the lakes and 



46 CHEMISTRY OF FARM PRACTICE 

rivers, even in temperate zones, would freeze from bottom 
to top into masses of ice which no summer sun would have 
power to melt. Under these conditions the circulation of 
water would be prevented and our latitudes would be well- 
nigh uninhabitable. 

When water under atmospheric pressure is heated to 
a temperature of 100° Centigrade, or 212° Fahrenheit, 
it assumes the gaseous form, and is known as steam. 

41. Solvent Action of Water. Water is the most widely 
distributed, and also the most important of solvents. It 
not only dissolves plant food, but also serves as a medium 
for its transportation from the soil to the plants. All of 
the plant food that is derived from the soil is taken up 
from solution; hence the solubility of the materials deter- 
mines their availability as plant food. 

Water charged with carbonic acid gas is the most im- 
portant natural solvent. In the decay of organic matter 
in the soil a great deal of carbonic acid and some nitric 
acid are liberated. This is one reason why it is desirable 
to incorporate a large amount of organic matter in soil. 
The nitric acid formed during the process of nitrification 
is a stronger solvent than carbon dioxide; but the quantity 
formed is comparatively small; hence the influence of 
the carbon dioxide as a solvent in the soil is believed to 
be greater than that of nitric acid. The nitric acid imme- 
diately reacts with the basic elements in the soils, such as 
calcium, sodium, potassium, magnesium, and ammonium, 
producing metallic nitrates, all of which are soluble. In 
this way, the plant may be furnished not only with nitrogen, 
but with potassium or calcium as well. Phosphoric acid 
and monocalcium phosphate are both soluble in pure 
water. Dicalcium phosphate, when present in soil, is 
insoluble in water, but it may be dissolved by treating 
it with neutral ammonium citrate of a specific gravity of 
1.09. Tricalcium phosphate is insoluble in water; but it 
is soluble to some extent in the soil moisture when the 



WATER— SOLVENT ACTION OF WATER, ETC. 



47 



soil is well supplied with decaying organic matter. It is 
probable that the carbonic acid in the soil solution is the 
most effective means for dissolving tricalcium phosphate, 
thus making it available as a plant food. 

Table II shows the difference between the solvent action 




Fig. 13. — The. shallow barnyard well, with privy vault and manure 
heaps near by. The water is likely to receive fluid from these 
any time. (From Smith's " Sewage Disposal on the Farm," 
Farmers' Bulletin, No. 43, U. S. Department of Agriculture.) 



of water charged with carbon dioxide and of distilled 
water. The marked increase in the solvent power of 
water when carbonated is clearly indicated. 

During the process of decomposition of organic matter, 
the nitrogen is changed in form. The organic compounds 
of nitrogen are changed .by the ammonifying bacteria into 



48 



CHEMISTRY OF FARM PRACTICE 



TABLE II.— THE SOLUBILITY OF CERTAIN MINERALS IN 
DISTILLED WATER AND IN CARBONATED WATER 



Name of 
Mineral. 


Composition. 


Parts per 

Million Soluble 

in Distilled 

Water. 


Parts per 

Million Soluble 

in Carbonated 

Water. 


Calcite 

Dolomite. . . . 

Apatite 

Gypsum 

Feldspar. . . . 

Mica 

Hematite. . . . 
Quartz 


CaC0 3 

CaC0 3 MgC0 3 

Ca 3 (P0 4 )2,CaCl 2 CaF2 

CaS0 4 -2H 2 

KAlSi 3 8 

H 2 KAl s (Si0 4 )3 

Fe 2 3 

Si0 2 


34 

25 

3 

2390 

20 
5 
2 
1 


980 
325 

10 

4600 

45 

8 
15 

3 



ammoniacal compounds. These compounds are oxidized 
by the activities of another group of bacteria into nitrous 
compounds, which are further oxidized by other bacteria 
into nitric compounds. The nitric acid thus produced 
forms, with the basic elements of the soil, soluble nitrate. 
Examples of these have already been mentioned. It should 
be remembered that all nitrates are soluble in water. The 
formation of nitric acid and its subsequent conversion of 
bases, formerly in insoluble compounds, into nitrates, which 
are soluble in water, and the increased solvent power of 
the soil water through carbonation, are examples of the 
natural solvents and their action. There are a number of 
organic acids both in the soil and in animal manures that 
have solvent powers p but the study of them requires a 
large mass of data which is as yet incomplete. It is suf- 
ficient to say that they exert marked activities in making 
available food for plants. 

42. Factors Influencing Availability of Plant Food. 
Nature provides that the more the soil is worked, the 
more responsive it becomes and the more plant food be- 
comes available. There are many factors influencing the 
availability of the plant food of the soil. We may mention 



WATER— SOLVENT ACTION OF WATER, ETC. 



49 



warmth, moisture, decaying organic matter, cultivation, 
aeration, and freezing as the most important ones. An 
abundant supply of organic matter in a soil, its proper 
cultivation to allow an abundant circulation of air, an 
abundant supply of moisture, avoiding an excess, and 
warm weather are the conditions best suited for nitrifi- 
cation. The effects of frost and winds are mainly physical, 



Shallow Shallow 

Dug Well Bored Well 



Deep Deep 

Dug- Well Bored Well 




Fig. 14. — Driven and dug wells showing the relative danger of drain- 
age contamination. (Farmers' Bulletin 549, U. S. Dept. Agr.) 



and result in more finely divided soil particles, affording 
more surface area for the activities of the natural solvents. 

43. Drinking Water. Impure water transmits many 
diseases, among which may be mentioned typhoid fever, 
dysentery, other diarrhceal affections, cholera, cholera in- 
fantum, animal parasitic diseases, enteric fever, tuber- 
culosis, and scarlet fever. Typhoid fever may also be 
spread by milk, raw fruit, shell fish, or flies. Scarlet fever 



50 CHEMISTRY OF FARM PRACTICE 

is more often spread by milk than by water; and cholera, 
dysentery, and cholera infantum are carried by milk to 
some extent. Enteric fever is carried by flies. Each of 
the above-mentioned diseases is spread by as pecific organ- 
ism, and this organism must first get into the water for 
the water to become a carrier of the disease. 

It has been estimated that approximately one-third of 
the water that falls runs off on the surface of the ground 
into streams. This water is termed the run-off. Two- 
thirds sinks into the soil, and of this, approximately one- 
half, or one-third of the total water, is lost by evaporation. 
This is termed the fly-off. The remainder, approximately 
one-third of the total rainfall, finds its way out in springs 
or through subterranean passages. This is termed the 
cut-off. The proportion of the run-off, fly-off and cut-off 
will vary with differing conditions, but the above esti- 
mate is generally approximately true. The cut-off is the 
water that interests us from the standpoint of sanitary 
water for rural homes. 

Farm homes are usually supplied with water from one 
of three sources: springs, shallow wells, or deep wells. 

(a) Spring water is contaminated, and may be infected, 
by coming in contact with filth of any kind; for this reason 
the water-shed of the spring should not have on it, draining 
toward the springs, any barnyards, pigsties, privies, slaughter 
houses, or graveyards. The spring should be well ditched 
around, so as to prevent its being overflowed, contaminated, 
and possibly infected. It is generally believed that the 
flowing of water through the soil purifies it, but this de- 
pends upon the character of the ground through which 
it flows. Under certain conditions (from a pathogenic 
standpoint) old water may be better than fresh water, 
because the germs have had time to die. 

(b) Shallow wells have been used as a source of water- 
supply since Biblical times. They are likely to become 
infected through seepage and incomplete filtration. The 



WATER— SOLVENT ACTION OF WATER, ETC. 



51 



open well and the chain and bucket should be discarded 
and a pump with a closely fitting well cover which does 
not leak, should be installed. Arrangements should be 
made for the removal of waste water and to prevent the 
seepage into the well of surface water. This can be accom- 
plished, preferably, by the use of cement, or a brick and 
mortar structure may be employed. In both cases the 
foundation should be laid well below the surface of the 
ground, as in Fig. 15, and upon this foundation the well 
cover should be placed. The well which is to supply the 
family with drinking water should not be located in the 

Water-tight 




>/;;//// 77-, 



Curb 



Water-proofed 
" Portland Cement 



^^^ 






Fig. 15. — Proposed method of protection of dug wells. (Farmers' 
Bulletin 549, U. S. Dept. Agr.) 



barnyard or near any of the sources of possible infection 
already mentioned in connection with spring water. No 
drains or sewer pipes should run near the well for fear of 
pollution, contamination, or possible infection with disease 
organisms. 

(c) Deep Wells. Where practicable, artesian wells, Fig. 
16, furnish our best source of water-supply. These wells 
may vary in depth from one hundred to twenty-five hundred 
feet. Where a flowing well can be obtained it will usually 
prove to be the best and most economical water-supply. 

After having seen to it that the drinking water-supply is 
as free as possible from infection, the factors that make for 



52 



CHEMISTRY OF FARM PRACTICE 



attractiveness of the water may be considered. These are 
taste, odor, color, turbidity, and sediment. The desirability 
of a good source and supply of water cannot be urged 
too strongly on the rural householder. It is an economic 
proposition, saving large sums in expense incident to sick- 
ness, and even more through increased efficiency. No man 
can work to best advantage when handicapped by poor 







%m 






Fig. 16.— Flowing well near Conway, S. C. (Photo by Prof. C. E. 

Chambliss.) 



health, which in many, cases is the direct result of a poor 
water-supply. 

44. Hardness in Water. Hardness in water is caused 
by the presence of metallic salts, usually those of calcium 
or magnesium, dissolved in the water. When soap is 
added to such waters, the fatty acid radicals of the soap 
combine with the calcium and magnesium and produce 
an insoluble curdy precipitate. Until all of these calcium 
and magnesium salts are thus precipitated, no lather can 



WATER— SOLVENT ACTION OF WATER, ETC. 53 

be obtained with the soap and it is useless as a cleansing 
agent. Hardness in water is consequently easily determined 
by adding a standard soap solution to the water, which 
will produce a greasy precipitate with the calcium and 
magnesium salts in the water. Not till these salts are 
all precipitated can a permanent lather be formed on the 
surface of the water. The quantity of the soap solution 
needed to produce the lather will, therefore, measure the 
hardness of the water. 

Hardness may be classified as temporary hardness and 
permanent hardness. Temporary hardness is usually caused 
by the presence of dissolved bicarbonates of calcium and 
magnesium. Permanent hardness is usually due to the 
chlorides and sulphates of these elements. Calcium and 
magnesium carbonates are insoluble, but if carbon dioxide 
is present in the water, they dissolve to some extent, forming 
the bicarbonates. Water having much hardness is objec- 
tionable for drinking purposes. For bathing and laundry 
purposes, it is expensive on account of the large amount 
of soap incident to its use. 

Table III shows the relative efficiency of a number 
of soaps for the purpose of softening water as given by 
Whipple : 

According to Alexander Smith, with water containing 
35 grains of hardness per gallon (60 parts per 100,000), 
6 pounds of soap are wasted per 100 gallons of water before 
the part of the soap that is to do the work of cleansing 
begins to dissolve. 

When we consider that for each one part per million 
of hardness it requires ten dollars' worth of soap to soften 
one million gallons of water, it emphasizes the expense 
in the use of hard water as a detergent. 

Temporary hardness may be removed: 

(1) By heating the water to boiling, so as to expel 
carbon dioxide, in this way converting the soluble bicar- 
bonate into an insoluble carbonate; 



54 CHEMISTRY OF FARM PRACTICE 

TABLE III.— EFFICIENCY OF SOAPS IN SOFTENING WATER 







So 


Number of Gallons of 


Water Softened by C 


ne Poc3*d of 




"T3 u 

a o 


03 w 

so 






















M 

ft 


03^*1 

°I ■ 


a; 




>> 
-3 










a 

o3 


03 


te 

a 


t 

03 

Pj, . 

m 

is 


u"3 £ 
ScO « 

g o3iO 


o a 

«« a 

O cj . 
l, O t, 

5 03t> 


m 
a 
O 

c3 d 
a ° 


a 

o3 
o 

CO 

>> 

p 


c 

3 
o3 

tn 

S d 


d 

"o 
a 

c3 


a 
< 

o 


3 


"o 


6 

03 

99 


o 
co 
-o 
a 

W 

8 

03 


Id 
Oi 03 

O o 

CO 

JD 


^5o 


w 


fe 


fe 


QD 


M 


pq 


CO 


pq 


O 


Ph 


Ph 


O 


<< 


20 


2.1 


1.11 


409 


196 


138 


102 


143 


165 


167 


187 


225 


167 


25 


2.4 


1.27 


358 


174 


121 


90 


125 


145 


147 


164 


206 


147 


40 


3.6 


1.91 


238 


115 


80 


59 


83 


96 


98 


109 


137 


97 


50 


4.3 


2.28 


200 


96 


67 


50 


70 


81 


82 


92 


115 


82 


75 


6.1 


3.24 


140 


67 


47 


35 


49 


57 


58 


64 


80 


57 


80 


6.4 


3.49 


140 


70 


44 


33 


45 


52 


53 


60 


75 


54 


100 


7.8 


4.13 


110 


53 


37 


27 


38 


44 


45 


50 


63 


45 


125 


9.5 


5.04 


90 


43 


30 


25 


31 


36 


37 


41 


52 


37 


150 


11.1 


5.89 


77 


37 


26 


19 


27 


31 


32 


35 


44 


31 


175 


12.7 


6.74 


67 


32 


23 


17 


23 


27 


28 


31 


38 


27 


200 


14.3 


7.59 


60 


29 


20 


15 


21 


24 


25 


27 


34 


24 



(2) By treating the water with lye, sodium hydroxide, 
CaH 2 (C0 3 ) 2 + 2NaOH = CaC0 3 + Na 2 C0 3 +2H 2 ; 

(3) By treating with milk of lime, 

CaH 2 (C03)2+Ca(OH)2 = 2CaC03+2H 2 0. 

Permanent hardness is removed by treating the water 
with sodium carbonate. The following equation may repre- 
sent the reaction: 

CaS0 4 + Na 2 C0 3 = CaC0 3 + Na 2 S0 4 . 

The calcium carbonate in all these cases, being insoluble, 
will be precipitated from the water, leaving in the water 
sodium salts, which are not particularly harmful. 

Magnesium and iron salts react similarly to the cal- 



WATER— SOLVENT ACTION OF WATER, ETC. 



55 



cium salts, though the iron precipitates as the hydroxide 
when sodium carbonate is the precipitant. Iron is objec- 
tionable in laundry work. Sodium carbonate is objection- 
able in water used in locomotive boilers, because it induces 
foaming; it is also objectionable in water for irrigation 
purposes, causing the accumulation of alkali in the soil. 
Permanently hard water affects the paper maker, the 
tanner, the bleacher, and the dyer. 

45. Filtered Water. Thorough filtering makes water 




Fig. 17.— An effective sand filter. (Drawing by Mr. T. C. Hough.) 

more attractive for household use, as color, odor, turbidity, 
sediment, and to some extent, hardness may be removed 
and an infected water may be made safer for drinking 
purposes. City water-supplies are often treated in this 
way and improved. Fig. 17 shows an effective sand filter. 
The bottom of the filter, A, consists of puddled clay 2 feet 
in thickness, built in with stones 8 inches in thickness; 
layer B consists of coarse, angular stones and is about 30 
inches in thickness. The next layer, C, consists of 6 inches 
of smaller stones and over this is placed D, composed of 



56 CHEMISTRY OF FARM PRACTICE 

6 inches of coarse gravel, followed by E, 6 inches of fine 
gravel. The top layer consists of 30 inches of sand. Chan- 
nels (shown at X) are used to collect the water; they are 
situated half in the bed of clay and half in the large rocks. 
The best size of sand to use is 0.5-1.0 millimeter in diam- 
eter, and the greater the uniformity obtained in the size 
of the sand the better the nitration obtained. 

46. Boiled Water. Water is purified for drinking pur- 
poses by boiling. This method can easily be used and is 
quite inexpensive and effective. 




Fig. 18. — A simple apparatus for distilling water. 

47. Distilled Water. Distilled water is pure, but it 
needs aeration to become palatable, as it has a flat taste. 
In Fig. 18 is shown an apparatus for distilling water. 

48. Boiler Water. In limestone regions, we find hard 
water; in soils derived from sandstone and granite, soft 
water occurs. Water, however, does not always partake 
of the nature of the topsoil. Especially is this true when 
the sources of supply are wells, because the water may have 
come in contact with different strata below the surface. 
If possible, water to be used in boilers should be analyzed, 
and a suitable supply selected before installing the power 
plant; otherwise a hard crust or scale will deposit over the 



WATER— SOLVENT ACTION OF WATER, ETC. 



57 



boiler tubes. Bicarbonates and sulphates of calcium and 
of magnesium dissolved in water make up, generally, at 
least 90 per cent of its hardness. The presence of the 
two bicarbonates constitutes what is known as temporary 
hardness, which is more easily handled than permanent 
hardness; the presence of calcium sulphate and of mag- 
nesium sulphate constitutes permanent hardness. 




Fig. 19. — Scale removed from a boiler. (From Fower, Dec. 22, 1914.) 



The purification of boiler water may be accomplished 
by the methods given for household water, page 54. 
Temporary hardness may be removed by heating the 
supply in a tank before it enters the boiler, by means of 
waste steam or by any desirable method. This heating 
converts the rather soluble bicarbonate of calcium or of 
magnesium into the much less soluble normal carbonate, 
by expelling carbon dioxide, according to the following 
formula : 

Ca2H 2 (C03)3+heat = 2CaC03+H 2 0+C02. 



58 CHEMISTRY OF FARM PRACTICE 

The normal calcium carbonate (CaCOs) is soluble only 
to the extent of 2^ grains per gallon. Magnesium bicar- 
bonate, when heated, decomposes in the same way as cal- 
cium bicarbonate, although the normal magnesium car- 
bonate is soluble to the extent of 14 grains per gallon. 

As a second method, temporarily hard water may be 
softened by chemical means as already shown. Four 
pounds of quicklime will soften as much water as 80 
pounds of soap, hence the use of the lime will be far more 
economical. Needless to say, this treatment must take 
place in a different receptacle from the boiler. The reac- 
tion is the same as that previously given for milk of lime. 

Pure calcium carbonate does not produce a very hard 
scale at first, but it hardens with heating and drying. 
When it is heated rapidly, it deposits as mud; but when 
heated slowly it forms calcite, which will become a hard 
scale when baked. Magnesium carbonate behaves simi- 
larly to calcium carbonate. 

Permanently hard water is less desirable as a boiler 
supply. Calcium sulphate is more troublesome than cal- 
cium carbonate, because it forms a hard and adhesive 
boiler incrustant, beneath which the iron is often corroded 
and overheated. 

Boiler water may, also, be helped by filtration, al- 
though the suspended matter strained out by the filter 
as a rule does not cause a deposit of scale. One very 
simple precaution may save much trouble, never empty a 
boiler while it is hot, because the incrustation in that case 
will be baked on. Never blow out the boiler under steam 
pressure, because the incrustation, becoming dry, absorbs 
carbon dioxide from the air, which helps to fix the deposit 
more firmly. 



CHAPTER VI 



SOIL WATER 



49. Water Requirements of Plants. No one factor has 
a more important bearing on crop production than the 
proper amount of the right kind of soil moisture. Table 
IV has been compiled by Warrington from data obtained 
by the investigators named to show the number of pounds 
of water transpired by growing plants for each pound of 
dry matter produced : 



TABLE IV. 



-NUMBER OF POUNDS OF WATER EVAPORATED 
TO GROW CROPS ENUMERATED 



Lawes and Gilbert, 
England. 



Beans 214 

Wheat .... 225 

Peas 235 

Red clover. 249 
Barley 262 



Hellriegel, 
Germany. 

Beans 262 

Wheat. ... 359 

Peas 292 

Red clover 330 

Barley 310 

Oats 402 

Buckwheat 371 

Lupine . . . 373 

Rye 377 



Wollny 
Germany. 



Maize. . 
Millet.. 
Peas. . . 
Rape. . . 
Barley. . 
Oats . . . 
Buckwheat 664 
Mustard.. 843 
Sunflower. 490 



233 
416 
479 
912 

774 
665 



King, 
Wisconsin. 



Maize . . . 


. 272 


Potatoes . 


. 423 


Peas .... 


. 447 


Red clover 453 


Barley. . . 


. 393 


Oats. . . . 


. 557 



In general, it may be stated that from 200 to 500 pounds 
of water are required to produce 1 pound of dry matter 
of the ordinary field crops. The amount required is in- 
fluenced by the climate, the soil type, and the preparation 
and cultural methods employed. 

50. Soil Components. The soil is made up of three 
components, solid, liquid, and gaseous. The solid part 

59 



60 CHEMISTRY OF FARM PRACTICE 

consists of the inorganic and organic materials; the liquid 
part consists of water carrying more or less of mineral or 
of organic materials in solution; the gaseous part consists 
of air, mixed with carbon dioxide produced by the decom- 
position of organic matter, water vapor and other gases. 
The whole may be likened to an animal, the solid part 
forming the body, the skeleton of which represents the 
inorganic solids, while the flesh and muscles represent 
the organic solids; the soil water and its contents con- 
stituting the circulatory system of the animal, and the 
air and other gases the respiratory system. 

51. Soil Water. All plant food that enters the plant 
from the soil is transferred to the plant in solution; there- 
fore, we see that the plant food in the soil must become 
soluble in the soil water before the plant can use it for the 
building of its tissues. It is a wise provision of nature 
that the better treatment of the land accentuates the 
factors that promote solution, while poor methods of soil 
treatment make the plant food elements less soluble. 

The rainfall of the different sections of the United 
States is variable, ranging from about 100 inches in the 
most humid areas to as low as from 2 to 5 inches in the 
most arid regions. The rainfall most desirable for maxi- 
mum production is about 50 inches. When rainfall is- 
less, there is more reason for greater efforts toward con- 
servation of moisture. 

There are three forms of water in the soil : Gravitational, 
capillary, and hygroscopic. The gravitational or free water 
moves under the force of gravity. Generally it is more 
harmful than helpful, because it leaches soluble plant food, 
excludes the air, hinders bacterial action, reduces surface 
tension, and dissolves cementing materials. It is helpful 
to the extent that it is converted into the capillary form. 
Also it may serve to wash some harmful bodies out of 
the soil. 

The capillary moisture is the liquid film which surrounds 



SOIL WATER 



61 



soil particles. This form of moisture furnishes the plant 
with ahnost its entire supply of liquid food. When capillary 




=1 

o 
w 
w 

(5 

1 



a 

o3 



action is promoted by favorable conditions of the soil, 
moisture may be drawn up from the water table some 
distance below, the amount of rise being determined by 



62 CHEMISTRY OF FARM PRACTICE 

the cross-section area of the capillary spaces and by the 
strength of the liquid film at the upper surface of these 
spaces. The smaller the area of the capillaries the greater 
will be the distance through which the water will rise. 

Every care should be exercised to increase the supply 
of moisture by the prevention of evaporation and per- 
colation. The available moisture is increased and the 
surface washing is decreased by deeper preparation of 
the soil, which offers a larger reservoir for the retention of 
water. Then, too, surface washing can be greatly lessened 
by the practice of terracing, which is quite extensively 
used in the Southern States, and also by the use of rotations 
that do not have many clean-cultured crops in them. The 
evaporation can be greatly lessened by shallow cultivation, 
during the growing season, which serves to form a soil 
mulch, destroys the surface capillarity, and retains moisture 
very effectively. The retention of the largest possible 
amount of the moisture serves a two-fold purpose: It adds 
to the available moisture, which is often the limiting factor 
of production, and it lessens the surface washing. In no 
way are our clean-cultured, rolling lands depleted more 
than by surface washing, and its prevention is worthy of 
the close consideration of those who own or cultivate such 
lands. 

For best soil conditions, the gravitational water should 
sink deep into the soil as rapidly as possible, in order that 
the capillary action may be at its best. Where the drain- 
age is good, the gravitational water is no trouble. Deep 
fall plowing, the incorporation of organic matter, and com- 
paratively shallow cultivation after each rain, in order to 
form a soil mulch, are the secrets of the conservation of 
moisture. 



CHAPTER VII 
AIR IN SOILS 



52. Composition of the Atmosphere. The atmosphere 
consists mainly of a mixture of the two gases, nitrogen 
and oxygen, and contains in addition argon, variable quan- 
tities of aqueous vapor, and very small amounts of carbon 
dioxide, ammonia, hydrogen, and ozone. Under certain 
conditions other gases, certain salts, finely divided soil 
particles, and small particles of animal and vegetable matter 
may occur as incidental ingredients. Dry air contains about 
75 J per cent by weight of nitrogen, and about 23 per cent 
by weight of oxygen, the other elements and compounds 
mentioned being present in very small quantities in mois- 
ture-free air. Carbon dioxide is present on an average 
in the proportions of 4 parts of carbon dioxide to 10,000 
parts of air. This seems insignificant, but the tremendous 
weight of the atmosphere can be realized when we con- 
sider that this minute proportion is equivalent to 28 tons 
of carbon dioxide in the atmosphere over one acre of land. 
The atmosphere is continuously moving, so that the air 
over an acre of land is renewed many times during the 
course of a day, thus tending to keep the air, although a 
mixture, approximately of definite composition. Growing 
crops rapidly use up carbon dioxide in the process of build- 
ing up the plant structures, all of which are largely car- 
bonaceous. The ratio between oxygen and carbon dioxide 
is kept constant, the amount of oxygen used up by com- 
bustion and life processes being restored by the decomposi- 
tion of carbon dioxide by the chlorophyl of the growing 
plant and the discharge into the air of the oxygen thus 
produced. 

63 



64 



CHEMISTRY OF FARM PRACTICE 



The free nitrogen present in the air is inert and can- 
not be made use of by the plant directly for plant food, 
Certain parasitic micro-organisms living on the roots of 
plants have the power of converting the nitrogen of the 
air into a form which becomes available as plant food, as 
stated on page 38. There is another class of bacteria 
that live on decaying organic matter, which has the power 







5.43 8.23 



p- \m m\ P 




Fig. 21. — Texture of a typical bright tobacco land of Virginia and 
North Carolina. (U. S. Dept. Agr.) 



of " fixing " atmospheric nitrogen 
come available for plant growth, 
on decaying organic matter are said 
53. Soil Air. The composition 
upon the amount of organic matter 
with which it is decaying. The 
differs considerably from that of 



in a form that may be- 
The bacteria that live 
to be saprophytic. 
of the soil air depends 
present and the rapidity 
composition of soil air 
the atmosphere. The 



AIR IN SOILS 65 

volume of air contained in different soils is quite variable, 
and is affected by the soil structure, texture, organic matter 
and moisture content. 

The greatest changes in the composition of soil air 
are found in the air of clayey soils when the particles are 
extremely small. Clay particles may be flocculated into 
masses, or flocculated clay may be granulated, thus con- 
siderably changing the pore space in the soil and the volume 
of air that it will contain. 

The size of the soil particles, which determines texture, 
also affects the pore space and, consequently, the air con- 
tent of the soil. Soil particles are of varying sizes, and 
under field conditions, the soils of fine texture generally 
possess large air space. 

Organic matter is quite porous, and its effect in the 
soil is always to increase the volume of air. It is necessary 
to have a sufficient supply of air to promote the decay 
of organic matter. The main benefits of organic matter 
are gained through its decay. 

The more completely the pore spaces in soils are filled 
with water, the smaller the amount of air that will be pres- 
ent. Water is held by capillary attraction more securely 
when the particles are small than when large, the capillarity 
being greater in a soil of comparatively fine texture. The 
volume of air increases and the capillary water diminishes 
when larger particles or granules are present. Because 
of this the flocculation of the clay soils of bottom lands 
by the use of lime permits of better drainage and more 
complete aeration, thus greatly improving this type of 
soil. 

54. Effect of Carbon Dioxide on Decay. The very rapid 
decay of organic matter and the liberation of carbon dioxide 
in large volume might serve to decrease the rapidity of 
decay on account of the harmful effect of large percentages 
of carbon dioxide to certain of the organisms producing 
decay. The percentage of carbon dioxide liberated in 



66 CHEMISTRY OF FARM PRACTICE 

the soil is proportional to the rapidity with which the 
organic matter decomposes; for carbon dioxide is one of 
the main products of the decay of organic matter. Decay 
goes on most rapidly during the warm months of the year, 
when the crop is being produced. At the time that soil 
moisture will be most highly charged with carbon dioxide 
and its solvent powers most increased, plant food is most 
needed. It has been proved that the plant rc^ts absorb 
oxygen and give off carbon dioxide, which action has a 
tendency to increase the solvent power of the soil moisture 
in the immediate vicinity of the roots. 

The formation of carbonates by the reaction between 
soil bases and carbonic acid may be beneficial to the soil, 
as in the case of carbonate of lime, and, in moderate quan- 
tities, carbonate of magnesium. On the other hand, large 
quantities of the carbonates of sodium and of potassium 
are deleterious, as is seen in the alkali lands of the West. 
There is a tendency for carbonates of sodium and of potas- 
sium to deflocculate the clay and, consequently, harm- 
fully affect the tilth of the soil. 

55. Oxygen Must be Present. The oxygen of the air 
is very important in its effects; the process of decay is in 
reality oxidation. Some mineral compounds are oxidized., 
and their solubilities changed. Most vegetable materials 
are oxidized during the process of decay, the ash elements 
contained being brought into solution so that they may 
be made use of by growing plants, and carbon dioxide is 
liberated, which, in turn, promotes the availability of 
insoluble plant food from the mineral materials. Oxygen 
is necessary for the germination of seeds, the growth of 
plant roots, and in combination with carbon as CO2 for 
the formation of the carbohydrates stored up in plant 
structures. 

56. Factors Affecting Soil Air. The air content of the 
soil is affected by several factors. In the first place, there 
is an exchange of air between the air above the soil and 



AIR IN SOILS 



67 



the air within the soil. They come together at the sur- 
face of the ground, and this exchange is brought about by- 
diffusion, which is dependent upon the pore space within 
the soil. 

Diffusion is the mingling of gases into each other. It 
may be measured by the passage of a gas through a porous 
partition. It has been demonstrated that the rate of 




Porous Cup 



-Hydrogen. 



Fia. 22. — Diffusion of hydrogen through a porous cup. 



diffusion of a gas is inversely proportional to the square 
root of the density of a gas. The rapidity of diffusion 
may be shown by the apparatus in Fig. 22. Hydrogen 
surrounding the unglazed porcelain cup and air within 
it each diffuse through the pores of the cup, but the air, 
being nearly sixteen times as dense as hydrogen, will dif- 
fuse one-fourth as rapidly. The hydrogen will penetrate 
to the interior of the cup more rapidly than the air can 
diffuse outward, consequently there will be increased pres- 



68 CHEMISTRY OF FARM PRACTICE 

sure within the cup, which will exert pressure upon the 
water in the connecting bottle, forcing it in a spray from 
the tube. Should the bell jar with its hydrogen atmosphere 
now be removed, the hydrogen which now is within the 
cup will diffuse rapidly into the outside air and the de- 
creased pressure within the cup will be indicated by bubbles 
of air rising from the tube through the water in the bottle. 

Thorough tillage enlarges the pore space and aids dif- 
fusion; packing a soil decreases the pore space and the 
diffusion. When rain falls, the water fills much of the 
pore space, excluding a certain volume of air; but, as the 
water sinks into the soil, the air is forced after it, because 
of the pressure of the atmosphere above, filling the space 
made vacant by the sinking of the water. The volume 
of a gas is directly proportional to the temperature and in- 
versely proportional to the pressure. The warmer the tem- 
perature, the greater the volume of any gas, and the greater 
the pressure, the smaller will be the volume occupied by 
a given gas. Under climatic conditions, there are con- 
stant changes of both temperature and pressure, which 
bring about movement of the soil atmosphere. 

57. Means of Producing a Change of Soil Air. The 
means at our disposal to produce change of soil air are 
tillage, under drainage, rotation, manures, and lime. 

Thorough tillage induces more exchange of air between 
the atmosphere above the surface and the air beneath the 
surface. Underdrainage removes superfluous water and in- 
creases the pore space that is rilled by air, thus allowing 
a freer circulation within the soil. Irrigation induces change 
in soil air in the same manner that rain induces change. 
The influx of water to a large extent excludes the air from 
the soil, and, as the water sinks into the soil, the pore 
space is refilled with air. Rotation of crops aids in the 
proper aeration of a soil, because the root systems of the 
different crops grown in the rotation are confined to dif- 
ferent soil strata, and, as old roots decay through the 



AIR IN SOILS 69 

process already mentioned, air passages are formed in 
the soil. Animal manures exert an influence on the texture 
of the soil, which enlarges the pore space. Applications of 
lime affect the structures of certain soils very materially, 
causing a rearrangement of the soil particles in such a 
way as to open the soil to an appreciable extent. 



CHAPTER Villi 
THE ASSIMILATION OF PLANT FOOD 

58. Source of Plant Food. The plant derives its food 
from two sources — the atmosphere and the soil. By far 
the greater portion is obtained from the atmosphere. Of 
the ten elements necessary for plant growth — carbon, hy- 
drogen, oxygen, nitrogen, phosphorus, potassium, sulphur, 
iron, calcium, and magnesium — carbon, hydrogen, and 
oxygen compose about 95 per cent of all agricultural crops. 
These three elements are supplied from the atmosphere. 
Some of the nitrogen used by plants is also derived indi- 
rectly from the atmosphere, from which it is " fixed " by 
means of bacteria (see page 38). The soil elements nec- 
essary for plant growth are taken up by the plants from 
water solution. The root system of the plant constitutes 
the channels for taking up the solutions. 

According to their root systems, plants may be divided 
into two main classes, those that have tap roots and those 
that have a mass of lateral, fbrous roots. The tap-rooted 
plants usually penetrate deeper into the soil. The main 
roots of the former class have smaller branches, and these, 
in turn, are covered with root hairs (Fig. 24) which are cells 
that act like syphons. They consist of cells which contain 
granular protoplasm and sap. These root hairs are widely 
distributed throughout the soil, and come in intimate con- 
tact with the soil particles. The soil particles are covered 
with capillary moisture containing certain amounts of 
plant food which has been dissolved from the particles. 
This moisture with its dissolved material is taken up by 
the root hairs and conveyed by osmotic pressure into the 

70 



THE ASSIMILATION OF PLANT FOOD 



71 



plant. The portion of the plant root that is covered with 
root hairs does not elongate. The root elongates from 
the growing tip. 




Fig. 23. — The root system of a corn plant to a depth of three feet. 
(From McCall's " Studies of Soils.") 

59. Osmosis. When two solutions are separated by a 
membrane, the weaker solution will flow towards the stronger 
solution, because water readily passes through the membrane, 



72 



CHEMISTRY OF FARM PRACTICE 



while the solution containing the greater amount of material 
will flow more slowly, being obstructed by the membrane. 
The inflow of water into the plant is thought to be in re- 
sponse to the pressure thus generated, the cell wall of the 
root hair being the membrane and the sap within the cell 




H 



Fig. 24.— (a) Root hairs, (b) 
close contact of root hairs 
with soil particles. 




Fig. 25. — Osmosis shown with 
a bladder membrane. 



being more concentrated than the soil solution. The dif- 
fusion of the plant food from cell to cell throughout the 
plant is considered to be due to the same cause. 

Every element or compound in the soil solution has 
its specific relationship to osmosis and, in this way, the 
amount of ea®h material imbibed is governed. Some 



THE ASSIMILATION OF PLANT FOOD 73 

excretions due to the slow passage of the denser liquid 
from the plant take place through the root hairs, but this 
is very small considering the amount taken in, the greater 
quantity going to the side of the stronger solution, i.e., 
into the plant. The solution containing the plant food 
finds its way through the stems of the plant to the leaves; 
there it comes into the " laboratory " of the plant, and 
in contact with the elements derived from the atmosphere. 

60. Function of the Leaves of Plants. The water 
which serves as the carrier of plant food from the soil 
originally comes from the atmosphere in the form of rain 
water. Carbon diox'de comes from the atmosphere, and 
is taken into the plant through small openings in the leaf, 
known as the stomata. The stomata form the breathing 
pores of the plants. Through them carbon dioxide is taken 
into the plant and oxygen is given off. In the leaves of 
the plant, all of the various elements of plant food are 
brought together and are built up into the proximate con- 
stituents of the plant. This process is termed photosyn- 
thesis. Photosynthesis takes place only in plants which 
contain green coloring matter. The material that produces 
the green coloring of plants is known as chlorophyl. 

The simplest photosynthesis is that in which formalde- 
hyde is produced. This is made into carbohydrates. The 
process is accomplished in the leaves of the plants under 
the influence of chlorophyl, sunlight, and aqueous carbon 
dioxide. It may be expressed in chemical equation: 

C02 + H 2 = CH 2 0+02, 
6CH20 = C 6 H 12 06. 

Carbon dioxide and water yield formic aldehyde (CH 2 0) 
and oxygen. The oxygen given off serves to replenish 
the atmosphere and aids in maintaining the balance be- 
tween plant and animal life. Six molecules of formic 
aldehyde, by condensation, form sugar (CeH^Oe). The 
sugars are soluble, and it is in this form that the carbo- 



74 



CHEMISTRY OF FARM PRACTICE 



hydrates are transported to different parts of the plant, 
where they lose water, according to the reaction 

C 6 Hi20 G = C G Hio05+H 2 0. 

The material is then stored in the form of insoluble starch 

(CeHioOg). 

The formation of the proteid compounds (nitrogenous) 
is more complex, but it, too, is carried on in the laboratory 
of the plant, the leaves. The rapidity of growth is dependent 
upon leaf area. This fact should be carefully considered, 
and too close clipping of grass in pastures should be avoided, 
because such cropping lessens the size of the factory that 
is building more grass. 

61. Leaching. It has been shown that some of the 
plant food may be leached out of the plant into the soil 
by rains, and may possibly again be made use of by the 
same pknt for the development of other parts of the plant. 
Hopkins gives the following tabular extracts from Le 
Clerc's lectures on this subject: 

TABLE V.— PLANT FOOD REMOVED FROM PLANTS BY 
LEACHING WITH WATER ON BASIS OF PER CENT OF 
TOTAL CONTENT 



Plants Leached. 



Wheat, in early bloom 

Wheat, fairly ripe 

Wheat, dead ripe 

Oats, from 8 ins. in height to ripe- 
ness; total removed by repeated 
leaching 

Potato vines 



1 

7 

25 




33 
21 



33 
50 



4 
54 
65 



36 
30 



10 
46 

58 



45 
12 




34 
55 



40 
9 



12 

41 
56 



23 
30 



60 
90 



40 
50 



THE ASSIMILATION OF PLANT FOOD 75 

Similar experiments have been conducted by German 
investigators. These investigations show that little plant 
food is leached during the early stages of growth, 
but that there is considerable leaching as the ripening 
proceeds. 



CHAPTER IX 

THE FORMATION, COMPOSITION, AND FERTILITY OF 

SOILS 

62. Formation of Soil. At one period in the history of 
the earth, its entire crust was igneous rock. Many agencies 
have been working through untold ages to develop the 
soil into its present condition. The weathering of rock 
has proceeded at different rates, being governed by the 
activities of the agencies involved. Weathering is brought 
about by chemical, physical, and biological means. The 
agencies of weathering are the atmosphere, water, heat, 
cold, gravitation, electrical discharges, and organisms. 

The chief action of the atmosphere is chemical, brought 
about mainly through oxidation and the solvent effects 
of carbon dioxide in solution. The atmosphere also exerts 
physical influences that hasten rock decay. Winds blow 
particles against other particles, producing abrasion, and 
by blowing against trees and plants, cause them to act 
as levers, which press the soil particles against each other, 
thus causing them to grind and wear one another away. 

Water, in addition to its solvent action, has a physical 
influence on the soil, in that rainfall causes the rubbing 
together of soil particles, thus producing some erosive effect. 
Surface water causes the wearing of soil particles against 
each other and thus increases their fineness. The erosion 
of the land tends to reduce the soil nearer to a base level. 

Heat and cold have the same physical effects on rocks 
that they have on other substances, rocks expanding when 
heated and contracting on cooling. The units which go 
to make up rocks are minerals. Different minerals have 
different rates of expansion and contraction, consequently, 

76 



SOIL FORMATION, COMPOSITION, ETC. 



77 




78 CHEMISTRY OF FARM PRACTICE 

when sudden changes of temperature occur, there is a 
tendency to break up the rock. The surface of the rock 
is subjected to more rapid changes, due to outside influence 
of heat and cold, and this influence tends to form flakes, 
cracks, and crevices, even on the outer surface of the same 
mineral. Water is retained in the cracks and crevices, and 
exerts its solvent influences. Then also, when water cools, 
it first contracts, becoming densest at 4° Centigrade, then 
expands till the temperature falls to zero. These changes 
of volume tend to break up rocks. When the water freezes, 
there is a sudden expansion by which such enormous pres- 
sure may be exerted as to shatter the strongest rocks. 

After soil is formed in the crevices of rocks, plants 
grow, and the roots of these plants have a solvent effect 
on the rock, due to the excretion of sap. Later, when 
more soil has formed, trees may grow between the rock 
masses, exerting a powerful force tending to separate the 
masses. In addition to this action of plants and trees 
in separating masses of rock, minute plant organisms, such 
as lichens and mosses, grow on rock surfaces and form soil 
which is either washed off or deepens until it furnishes a 
home for higher orders of plants, which in turn are followed 
by trees. These growing trees and plants get their plant 
food from deep down in the soil, and drop their leaves on 
the surface of the ground. The decay of these leaves 
impregnates the soil moisture with carbon dioxide, in 
which condition it has a much greater solvent effect on 
the mineral portion of the soil underneath. The soil layer 
is thus continuously deepened through additional deposits 
above and the continued solution of the rock beneath. 

Glaciers have exerted in past ages a powerful influence 
on soil formation. These vast ice fields crept slowly south- 
ward, grinding the rocks beneath them to a condition of 
great fineness. Some of the richest soils of the world are 
of glacial origin. 

Rivers emptying into the ocean, on account of the 



SOIL FORMATION, COMPOSITION, ETC. 79 

checking of the current and the action of the salts in the 
sea water, deposit the materials carried in suspension. These 
materials gradually accumulate on shallow bottoms until 
marsh lands are formed, and the building is continued 
through the action of winds, waves, tides, and plants until 
soil is gradually formed. There are many organisms in 
the ocean, such as coral polyps and shell-fish, that build 
up islands. The sea bottom is the seat of many soil- 
forming activities, and vast areas of sea bottom have been 




Fig. 27. — Residual soil, Piedmont region. (By permission F. G. 
Tarbox, S. C. Exp. Station.) 

elevated to form some of our most fertile soils. Sandstones, 
shales, and marls are formed at the bottom of the ocean. 

63. Composition of Soils. About ninety-eight per cent 
of the earth's solid crust consists of the eight elements: 
oxygen, silicon, aluminium, iron, calcium, potassium, sodium, 
and magnesium, here arranged in the order of their abun- 
dance. These elements make up the common minerals, 
which, in turn, make up the common rocks. 

The difference in the chemical composition of different 
soils is due to the differing compositions of the rocks from 



80 



CHEMISTRY OF FARM PRACTICE 




o3 

d 



SOIL FORMATION, COMPOSITION, ETC. 81 

which the soils are derived, the method of rock decay, 
and the conditions under which it has existed since its 
formation. The soils that have remained where they were 
originally formed are of two kinds, residual and cumulose, 
the latter being the result of the accumulations of plant 
residues. The residual soil is the result of rock decay, 
and represents the portions of the products that remain 
on the parent rock. This consists, in a large measure, of 
the elements most insoluble, which, however, represent but 
a small part of the original rock. There is very little car- 
bonate of lime in residual soils; even those derived from 
limestone rock are often deficient in calcium carbonate, 
the soil itself being sLnply the remains of the impurities 
in the original lmestone rock. The carbonate of lime has 
been converted into soluble calcium bicarbonate, when it 
has come in contact with water containing carbon dioxide, 
and then it is leached out of the rock. Soils derived from 
granite or gneiss are generally of a clayey nature. Soils 
from marine for nations are often sandy. Both classes 
grade into clay loan or sandy loam as the case may be. 

The transported soils are formed from the products of 
rock decay mixed with a certain amount of organic matter. 
These materials have been transported from the place where 
they were formed by such agencies as water, ice, wind, 
and gravity. Their composition will vary to a consid- 
erable degree. 

Soils that have been transported by water are classified 
as marine, alluvial, and lacustrine. Marine soil is formed 
by the deposits in the ocean beds, which are subsequently 
elevated. Alluvial soils are formed by the deposition of 
material along the shores of streams, and are very variable 
in composition. Lacustrine soils are formed in the beds 
of lakes or ponds which are subsequently drained. 

The wind-borne, or aeolian, soils are rather extensively 
represented by the loess soils of the central parts of the 
United States. This wind -deposited soil covers to varying 



82 



CHEMISTRY OF FARM PRACTICE 



depths parts of the Mississippi basin. The loess deposits 
extend from Illinois and Iowa as far south as some parts 
of Mississippi. 




Fig. 29.— Saprophytic plants called "frog stools" indicate that 
decay has begun. (Farmers' Bulletin 468, U. S. Dept. Agr.) 

The gravity-moved soils are termed colluvial, and are 
not very extensive. 

64. Gain and Loss of Plant Food. Two sets of factors 
affect the fertility of soil, both of which may be modified 



SOIL FORMATION, COMPOSITION, ETC. 83 

by artificial means. One set of factors tends to impoverish 
the soil; the other set is constructive. It is necessary 
to distinguish those factors which exhaust the soil from 
those which build it up, and to know how to minimize the 
former and to magnify the latter. In the natural state, 
there usually is a process of enrichment due to the accu- 
mulation of plant food elements in the surface soil. These 
elements are left in the residues of decaying organic matter. 
In the process of decay, the organic matter furnishes food 
for myriads of bacteria, some of which have the power of 
fixing the nitrogen of the atmosphere in a form that plants 
can make use of for their growth. These organisms must 
not be confused with the bacteria that exist in symbiotic 
union with legumes, and fix nitrogen in such a form that 
either the legume or a companion crop may make use of 
it. The bacteria on legumes grow on living plants, and 
may be termed parasitic in their mode of life, while the 
bacteria that live on dead tissues may be termed saprophytic. 
There is a point reached in the accumulation of plant food 
in the soil from the plant residues at which the increase 
and the loss in plant food about balance, due to loss through 
leaching. 

65. Importance of the Rotation of Crops. When land 
is planted to clean-cultured crops, two sets of losses to the 
soil are operative; one, due to the amount of plant food 
removed in the crop, and the other due to the increased 
rapidity of nitrification brought about by cultivation, and 
consequently, increased losses through leaching. 

There are advantages incidental to rotation. It is a 
well-established fact that some plants take up greater 
amounts of some elements than do others; that some plants 
possess the power of taking their food from compounds that 
others are powerless to use. Some plants have a longer 
growing season than others, and although they may take 
as much food from the soil, yet the drain is lighter, owing 
to the longer growing season. The root systems of plants 



84 



CHEMISTRY OF FARM PRACTICE 



differ considerably, and the area occupied by the root 
system limits the area from which the plants feed. The 
cultivation of crops differs, and the influences of the culti- 
vation of a previous crop must be considered when we 
plan a rotation. 

The practice of the proper systems of rotation makes 
it possible to maintain, at low cost, the supply of organic 




Fig. 30. — Field of Cowpeas ready to plow under. (Farmers' Bul- 
letin 278, U. S. Dept. Agr.) 



matter in the soil. Organic matter may be supplied in 
the form of animal manures, but this source of supply 
is very limited when we consider the total area in culti- 
vation. Some organic matter is also accumulated in pas- 
tures and in woodland, but these methods of incorporating 
organic matter are quite slow. The incorporation of resi- 
dues from field crops, especially the leguminous crops, is 
the best method for increasing the amount of organic 
matter in the soil. 



SOIL FORMATION, COMPOSITION, ETC. 



85 



TABLE VI.— THE CONTENT IN PLANT FOOD OF CERTAIN 
AIR-DRIED LEGUMINOUS CROPS 



Red clover, medium 

Red clover, mammoth . . . 

Alsike clover 

White clover 

Crimson clover 

Alfalfa 

Cowpea 

Bean 

Vetch 



Percentage Composition. 



Nitrogen (N). 



2.07 
2.23 
2.34 
2.75 
2.05 
2.19 
2.50 
1.91 
2.80 



Phosphoric 
Acid (PaOs). 



0.38 
0.55 
0.67 
0.52 
0.40 
0.51 
0.52 
0.40 
0.75 



Potash (K 2 0). 



2.20 
1.22 
2.23 
1.81 
1.31 
1.68 
1.47 
1.32 
2.30 



TABLE VII.— COMPOSITION OF VARIOUS CROP RESIDUES 



Corn stalks 

Wheat straw 

Oat straw 

Cotton bolls 

Cotton leaves 

Cotton stems 

Cotton roots 

Cowpea vines 

Alfalfa 

Soy bean straw 

Red clover, medium . . . 
Red clover, mammoth . 

Alsike clover 

White clover 

Crimson clover 

Pasture grasses (mixed) 

Timothy 

Orchard grass 

Sorghum 

S. potato vines 



Percentage Composition. 



Nitrogen (N). 



0.80 
0.59 
0.62 
1.36 
2.37 
0.83 
0.17 
2.50 
2.19 
1.75 
2.07 
2.23 
2.34 
2.75 
2.05 
0.91 
0.48 
0.43 
0.23 
2.00 



Phosphoric 
Acid (P2O5). 



0.18 

0.12 
0.20 
0.40 
0.46 
0.22 
0.24 
0.52 
0.51 
0.40 
0.38 
0.55 
0.67 
0.52 
0.40 
0.23 
0.26 
0.16 
0.09 
0.28 



Potash (K2O). 



1.04 
0.51 
1.24 
2.90 
0.83 
0.92 
0.86 
1.47 
1.68 
1.32 
2.20 
1.22 
2.23 
1.81 
1.31 
0.75 
0.76 
0.76 
0.23 
2.81 



86 CHEMISTRY OF FARM PRACTICE 

Rotation encourages diversified farming, which, when 
properly carried on, greatly aids in keeping the land in 
good condition. When the single -crop system is employed, 
if that crop is a clean-cultured one, as is usually the case, 
the organic matter of the soil becomes depleted, the soil 
erodes more easily and, consequently, " gullying " sets in. 
When land once begins to wash, it is difficult to keep the 
most valuable part of the soil from being lost. The top- 
soil is the most active in furnishing plant food and in pro- 




31. — A cover crop on corn land. (Permission F. G. Tarbox, 
S. C. Exp. Station.) 



moting plant growth. When this soil is washed away, 
the land becomes unproductive and it takes many years 
of careful building to restore it to its former fertility. The 
rebuilding of soil is time-consuming and expensive, there- 
fore care should be exercised to prevent erosion. Erosion 
may be prevented by the incorporation of organic matter, 
deep plowing, and, in some cases, by terracing. 

66. Proper Sequence of Crops. In arranging rotations, 
the endeavor should be to avoid having a crop that feeds 



SOIL FORMATION, COMPOSITION, ETC. 87 

heavily on a particular element, followed by another crop 
that feeds heavily on the same element; nor is a crop 
that requires a large amount of any particular element 
adapted to a soil that does not contain a fair amount of 
that element. Shallow- rooted crops should be followed 
by deep-rooted crops; clean -cultured crops as much as 
possible by crops that will leave much organic matter to 
be incorporated in the soil. Leguminous crops should be 
used frequently in rotations, in order that the largest 
amount of the expensive element, nitrogen, may be obtained 
from the supply that exists in the atmosphere. It is only 
when a high-priced crop is being grown that a farmer 
can afford not to rotate his crops. 

67. Use of Manures. When manure is intelligently 
conserved, a profit can be made by feeding leguminous 
crops to stock and, while obtaining profit on the increase 
in flesh, recovering most of the fertilizing elements in the 
manure, i:i a better state of mechanical division than it 
was as plant tissue. It does not follow necessarily, however, 
that the plant food will be more available in manure than 
in the plant tissues. The question for the farmer to de- 
cide is, whether or not it is more economical for him to 
feed the crops to animals, conserve the manure and apply 
it to his soil, or to incorporate the organic matter from 
the crops directly in the soil. Hopkins, in his " Soil Fer- 
tility and Permanent Agriculture," gives the table on 
page 88, showing that a large part of the organic matter 
during the processes of digestion and assimilation is decom- 
posed into carbon dioxide and water, and that little 
over 25 per cent of the dry matter is recovered in the 
manure. 

Doubtless, the best practice for the farmer to follow 
will depend upon the money value of the crop that he 
grows. If, for example, a valuable crop is to be grown for 
market, it will pay to grow a previous crop and incor- 
porate it in the soil, provided the increased yields of sue- 



88 CHEMISTRY OF FARM PRACTICE 

TABLE VIII.— THE AVERAGE DIGESTIBILITY OF SOME 
COMMON FOOD STUFFS 



Food Stuffs. 



Pasture grasses. . . . 
Red clover, green. . 
Alfalfa, green 

Mixed meadow hay 
Red clover hay. . . . 
Alfalfa hay 

Oat straw 

Wheat straw 

Corn stover 

Shock corn 

Corn-and-cob meal. 
Corn ensilage 

Oats 

Corn 

Wheat bran 



Percent Digested 

of Total in 

Food. 



Dry 

Matter. 



71 

66 
67 

61 
61 
60 

48 
43 
60 

63 
79 
64 

70 
91 
61 



Nitrogen. 



70 

67 
81 

57 
62 

74 

30 
11 
45 

42 
52 
49 

78 
76 
79 



Dry Matter of 

Food: Recovered 

in Manure. 



Percent. 



29 
34 
33 

39 
39 
40 

52 
57 
40 

37 
21 
36 



9 
39 



Pounds 
per Ton. 



580 
680 
660 

780 
780 
800 

1040 

1140 

800 

740 
420 
720 

600 
180 
780 



ceeding crops will more than repay for the value of the 
crop returned to the soil. If, on the other hand, the crops 
grown will not fulfill the above requirements, it will pay 
to use the plants for feed, and to carefully conserve the 
manure. However, it has been shown that there is a con- 
siderable loss in organic matter, due to the exhalation of 
carbon dioxide by the animals to which the material is 
fed. There is a further loss of nitrogen due to the forma- 
tion of muscle and sinew, which contain a large percentage 
of this element; and of phosphorus and potassium due to 
the formation of bone. From the foregoing statements, it 



SOIL FORMATION, COMPOSITION, ETC. 



89 




« o 



a 
o 

a 

I 

§• 

u 

o 



90 CHEMISTRY OF FARM PRACTICE 

can readily be seen that a young and growing animal will 
remove considerably more plant food and use it in the 
elaboration of tissue than will a mature animal. Another 
factor influencing the composition of the manure will be 
the composition of the feed. The third factor, which is 
probably the most important of all, is the care of the 
manure. If, after carefully considering his own conditions, 
the farmer decides that it is more profitable for him to 
feed the crop and return the manure to the land, which 
is usually the decision reached in diversified farming, there 
are several factors still to be considered; these will be 
discussed in the following chapter. 

68. Keeping the Land Covered. Under the prevailing 
methods of crop growth, the land is allowed to lie bare a 
part of the year. During this time, especially if the weather 
is warm, there is some nitrification going on, and much 
plant food is lost through leaching. It is good practice 
to keep a growing crop on the land "as much as possible, 
to take up the plant food as it becomes available and con- 
vert it into an organic form. If such a crop is planted as 
a winter protection to the soil, it is known as a cover crop. 
The cover crop is a material aid in the prevention of 
washing, because it fills the soil with fibrous roots which 
tend to hold the soil together. When a crop is planted 
between two other crops, it is known as a catch crop. An 
example is the planting of cowpeas or soy beans after 
grain has been harvested and before another grain crop is 
planted. 

When leguminous plants can be used for cover or catch 
crops, or in connection with other crops used for this pur- 
pose, they serve another purpose; that of collecting nitro- 
gen from the atmosphere and storing it in such a form 
that it is available as plant food. A more general use of 
cover crops and catch crops, especially of the legumes, 
will mark a great step forward in our agricultural devel- 
opment. For cover crops, clovers, vetch, oats, and rye 



SOIL FORMATION, COMPOSITION, ETC. 91 

are excellent. For Southern conditions, soy beans and 
cowpeas for summer crops, and vetch, oats, and rye for 
winter, are most easily grown, though crimson clover, red 
clover, and burr clover are excellent when established. 
At the North, the clovers are favorites, because they may 
be included in the regular rotations. 



CHAPTER X 
ANIMAL MANURES 

69. Quality. The quality of animal manure depends 
largely upon three factors: The composition of the feed, the 
age of the animal fed, and the handling to which the manure 
is subjected. The causes which account for the influence of 
the age of the animal have already been discussed in Sec. 
67, and they show the importance of feeding mature animals 
as much as practicable, where the composition of the manure 
is a consideration. The use of feeds rich in nitrogen, 
phosphoric acid, and potash, where the price of such feeds 
permits, produces the most valuable manures. Cottonseed 
meal, a feed rich in the elements named, sells for a reasonable 
price, and can be fed in moderation to advantage to all 
farm animals except hogs. It is the cheapest source of 
protein on the market. In buying feeds and in com- 
pounding rations, the plant food content of the feed should 
receive consideration. 

70. Liquid Manures. It is very important that an abun- 
dant supply of absorbent litter be used in the stables, to 
take up the liquid manure. It is best to use a litter that 
readily nitrifies and that carries as high per cent of plant 
food as possible. Table IX gives the compositions of some 
materials suitable for bedding. Some of the materials, corn 
stalks for example, should be shredded before being used. 

Table X emphasizes the fact that most of the nitrogen and 
potash is voided in the liquid manure, and it further shows 
that an abundant supply of absorbent litter should be used 
to conserve properly the liquid manure. The manure fur- 
nishes an excellent medium for bacteria, and, consequently, 
hastens the availability of the plant food in the litter. 

92 



ANIMAL MANURES 



93 



TABLE IX.— MATERIALS SUITABLE FOR BEDDING 



Corn stalks 

Wheat straw 

Oat straw 

Rye straw 

Marsh hay 

Sweet potato vines . . 

Cotton bolls 

Cotton leaves 

Cotton stems 

Long-leaf pine straw 
Short-leaf pine straw 



Phos. Acid, 
Per Cent. 



0.30 
0.12 
0.20 

0.28 
0.36 
0.28 
0.40 
0.46 
0.22 
0.24 
0.15 



Nitrogen, 

Per Cent. 



0.70 
0.59 
0.62 
0.46 
0.97 
2.00 
1.36 
2.37 
0.83 
1.00 
0.77 



Potash, 
Per Cent. 



1.40 
1.51 

1.24 
0.79 
1.46 
2.81 
2.90 
0.83 
0.92 
0.41 
0.21 



TABLE X.— THE CONTENT OF PLANT FOOD PRESENT IN 
SOLID AND LIQUID MANURE, ACCORDING TO VIVIAN 





Nitrogen, 
Per Cent. 


Phosphoric Acid, 
Per Cent. 


Soda and Potash, 
Per Cent. 




Solid. 


Liquid. 


Solid. 


Liquid. 


Solid. 


Liquid. 


Horses 

Cows 

Swine 

Sheep 


0.50 
0.30 

0.60 
0.75 


1.20 
0.80 
0.30 
1.40 


0.35 
0.25 
0.45 
0.60 


trace 
trace 
0.125 
0.05 


0.30 
0.10 
0.50 
0.30 


1.50 
1.40 
0.20 
2.00 



TABLE XL— NITROGEN, PHOSPHORIC ACID AND POTASH 
PRESENT IN ROTTED MANURES 





Per Cent 

Phos. Acid 

(P2O0). 


Per Cent 
Nitrogen 

(N). 


Per Cent 
Potash 
(K2O). 


Horse manure, rotted 


0.40 


0.50 


0.50 


Cow manure, rotted 


0.30 


0.50 


0.45 


Sheep manure, rotted 


0.80 


0.65 


0.60 


Hog manure, rotted 


0.80 


0.60 


0.30 


Hen manure 


0.25 


1.30 


0.20 



94 



CHEMISTRY OF FARM PRACTICE 



71. Rotted Manures. Table XI shows that rotted 
sheep manure has a higher nitrogen content than any other 




rotted manure, and next to this comes hog manure. The 
nitrogen content of horse and of cow manure when rotted 



ANIMAL MANURES 95 

is nearly the same. The horse and the cow manure contain 
more potash than the manure from hogs. On the other 
hand sheep and hog manures run higher in phosphoric 
acid. An explanation of this can probably be found in 
the fact that the horse caid the cow largely make use of 
different sources of feed than those consumed by hogs and 
sheep. 

Horse manure ferments very rapidly under certain 
conditions, and the best method for the farmer to pursue 
is to haul the manure to the field frequently and apply it 
to a growing crop; but such method is often impracticable, 
dua to the extra labor entailed, inclemency of the weather, 
and the fact that there is not always a growing crop avail- 
abb. Where horse manure is kept in a pile for some time, 
it must be packed down sufficiently to prevent violent 
nitrification, followed by denitrification, which is known 
as firefanging. This latter condition results in the loss of 
much of the nitrogen, and the material is just as truly ashed 
in the firefanged spots as though it had been in the fire. 
When manures firefang, they heat and liberate gases both 
injurious and uncomfortable to the animals. There is 
little danger of firefanging of cow manure because this 
manure will not heat. 

72. Effect of Exposure to the Weather. In handling 
dairy cattle, it is absolutely necessary that the stalls be 
kept scrupulously clean. In such a case it may be advis- 
able that the manure be hauled out every day, if possible, 
and spread upon the land that has, or is soon to have, a 
growing crop. Preferably the manure should be plowed 
in as soon as possible. It has been shown at the Maryland 
Experiment Station that, when 80 tons of manure were 
exposed to the weather for a period of one year, the weight 
was reduced to 27 tons. At the Experiment Station of 
the Dominion of Canada, when 2 tons of manure, con- 
taining 1938 pounds of dry matter, were exposed for four 
summer months, the dry matter was reduced to 655 pounds 



96 CHEMISTRY OF FARM PRACTICE 

through the agencies of fermentation and decay. During 
the same time, the nitrogen content was reduced from 48.1 
pounds to 27.7 pounds. These experiments, as well as 
many more that could be cited, show the importance of 
applying the manure and incorporating it into the soil 
as soon as possible. 

73. Rate of Application. The rate of application of 
animal manures should vary considerably. It depends 
upon two factors: The supply of manure and the section 
of the country. The reason that the supply is a factor, 
is that manure is a good medium for the growth of bacteria, 
in addition to the plant food content; therefore it should 
be spread over as much land as practicable to furnish 
bacteria flora to the soil. Conditions affecting nitrification 
differ in various sections of the country. Thus the con- 
ditions prevalent in the southeastern part of the United 
States favor rapid nitrification; in fact, very noticeable 
results have been obtained in South Carolina from the 
use of only 2 tons of manure per acre, applied to cotton. 
On the other hand, the conditions existing further north 
favor slower nitrification; consequently, heavier applica- 
tions are necessary, but heavy applications under these 
conditions are more lasting in their influence. For general 
farm crops in the South, it is advisable to apply about 6 
tons of manure per acre, while in some Northern sections of 
the United States, from 12 to 20 ton applications frequently 
are made. 



CHAPTER XI 
AGRICULTURAL LIME 

74. Sources of Lime. Lime is found in limestone 
(mainly CaCOs) which is widely distributed over the United 
States, principally as calcite, dolomite, marl, chalk, and 
deposits of the shells of mollusks or other marine animals. 
Limestone, when burned, yields calcium oxide, called quick 
lime, which, when slaked with water and mixed with sand, 
is made into mortar. Dolomite is rock composed mainly 
of the carbonates of calcium and magnesium. Marl con- 
sists of calcium carbonate mixed with clay, or peat in 
varying proportions. Its calcium carbonate content ranges 
from 5 to 90 per cent. 

75. Effects of Lime on the Soil. Lime is beneficial to 
the soil on account of its chemical, physical, and biological 
effects. Lime also acts as a direct plant food; for cal- 
cium is one of the ten elements necessary for plant growth, 
although it is used by plants in less amount than is potas- 
sium or magnesium. Any of the soluble salts of calcium 
may serve to furnish the element calcium for plant food. 
However, only three forms — calcium oxide (quick lime), 
calcium hydroxide (slaked lime), and calcium carbonate 
(limestone) — serve to correct acidity of the soil. The cor- 
rection of acidity has an important influence on the devel- 
opment of the bacterial flora, and it also assists nitrification 
by furnishing a basic material to combine with the nitric 
acid which is formed when the nitrogen of the air becomes 
" fixed " or oxidized. 

The different compounds of calcium vary in their chem- 
ical action upon soil. Calcium oxide, or quick lime, being 
a caustic, is very active chemically. It decomposes organic 

97 



98 CHEMISTRY OF FARM PRACTICE 

matter, corrects acidity, furnishes the element calcium, 
and by means of its chemical activity reacts with other 
bases in the soil. An example of this last effect is found 
in the reaction between lime and the zeolites of the soil, 
which are the double silicates of aluminium and some other 
base, the base being changed by substitution of calcium 
due to the action of lime. In this way, lime may serve to 
liberate potassium, which must be present in available form 
in a fertile soil. Lime may also bring about reactions with 
the phosphates of iron or aluminium, the product being 
a phosphate of lime, which is more soluble. and therefore 
more available for plant food than the phosphates of iron 
or aluminium. 

Calcium hydroxide is produced by the action of water 
upon quicklime and is similar in its action to calcium 
oxide. When applied to the soil, calcium oxide is quickly 
converted into calcium hydroxide by moisture 

CaO+H 2 = Ca(OH) 2 , 

which, in turn, is rapidly converted by the carbon dioxide 
of the air into calcium carbonate 

Ca(OH) 2 + C0 2 = CaC03 + H 2 0. 

Calcium carbonate is not caustic, and consequently it is 
much less drastic in its effects than is the oxide or hydroxide. 
Carbonates are easily decomposed by acids, therefore the 
application of ground limestone serves to correct acidity 
in soils. In humid regions probably it is rapidly converted 
into calcium silicate. Calcium carbonate fulfills most of 
the functions performed by calcium oxide and calcium 
hydroxide, but it acts in a much milder manner. Calcium 
silicate (CaSiOs) and calcium sulphate (CaoSCU) or " land 
plaster," serve most of the functions of the other forms 
of lime except the correction of acidity, the effectiveness 
of the salts varying with their solubilities. 

Lime modifies the physical structure of soils. It tends 



AGRICULTURAL LIME 



99 



to flocculate clay, permitting a freer circulation of capil- 
lary water. It also serves to bind together sandy soils, 
making them more compact. The action of caustic lime 
on muck or peat soils is usually very beneficial: first, because 




Fig. 34. — Burning lime on the farm. Details of construction of a farm 
limekiln, a, Cross-section, showing layers of rock and coal; b, 
longitudinal section, showing side hill used as back wall; c, ground 
plan, showing trench and grate; d, completed kiln, walled in and 
plastered with mud. (Farmers' Bulletin 435, U. S. Dept. Agr.) 



it brings about the rapid destruction of organic matter, 
accompanied by the liberation of considerable amounts of 
soluble plant food; second, because it promotes the decom- 
position of the excess of organic matter, resulting in improved 
structure of the soil. When caustic lime is applied, there 



100 CHEMISTRY OF FARM PRACTICE 

is danger of depleting the organic matter in soils which 
are not well supplied with it, but this does not hold true 
for applications of calcium carbonate. In soils moderately 
well supplied with organic matter, the use of heavy appli- 
cations of caustic lime may lead to the liberation of more 
available nitrogen than the plants can use. In this case 
some plant food, especially nitrogen, will be lost. Exces- 
sive applications of -caustic lime, even to clay soils, may 
lead to the flocculation of the clay to such an extent that 
percolation will be too rapid. The flocculating power of 
lime may be illustrated by adding lime water or milk of 
lime to water containing clay in suspension, when it will 
be observed that the clay particles rapidly settle out. 

Caustic lime, when applied excessively, may exert a 
harmful effect on the soil bacteria, and temporarily arrest 
to some extent the useful functions performed by these 
agents; but this form of lime, when applied in moderate 
amounts, is usually quickly changed to a neutral salt, 
either calcium carbonate or calcium silicate. The former 
salt is still effective to correct acidity, but calcium silicate 
does not exert such an influence. 

The fact that continuous liming without manure makes 
land less productive than it formerly was, has led many 
people to object to the use of lime altogether. The initial 
application of lime produces such marked results, due to 
its influence on the stored plant food in the soil, that the 
fact that its effects are indirect is not recognized and there 
is a temptation to continue its use at the expense of the 
potential fertility of the soil. It is very unusual for the 
soil to contain such an insufficient supply of lime that 
lack of calcium becomes a limiting factor in plant growth. 

76. Shipping Lime. The main forms of lime marketed 
for agricultural purposes are " quick lime " (CaO), " water- 
slaked lime " (Ca(OH) 2 ) and " air-slaked lime " (CaC0 3 ). 
To ship agricultural lime a long distance involves large 
expense ; due to freight charges. A ton of water-slaked 



AGRICULTURAL LIME 



101 



lime, or calcium hydroxide, contains only 1513 pounds of 
calcium oxide, the remaining 487 pounds consisting of 
water, and a ton of air-slaked lime, or calcium carbonate, 
contains only 1120 pounds of calcium oxide, the remaining 
880 pounds being composed of carbon dioxide, while quick- 
lime should be pure calcium oxide. On this basis of com- 
parison, we see that it is much more expensive to freight 
a given amount of calcium in the carbonate or hydroxide 
form than in the oxide form. In shipping, it is necessary 
that the quicklime and water-slaked lime be barreled or 
sacked, because by exposure to moisture and air both of 
these materials are transformed into air-slaked lime, and 
also on account of the difficulty of loading and unloading 
these caustic materials. The air-slaked lime, or ground 
limestone rock, which are each calcium carbonate, and 
not caustic, may be handled without containers. 

The same condition holds for hauling the different 
forms of lime from the railroad station to the farm that 
held in the freight charges. It is most economical to haul 
the quicklime, the water-slaked costing somewhat more, 
and the carbonate of lime is most expensive for cartage, 
though the carbonate is the most easily handled. A smaller 
application of caustic lime will produce more marked 
effects than will a larger application of carbonate of lime, 
although the latter is more lasting in its influences. The 
amounts of other forms of lime which are equivalent to a 
ton of quicklime are given in Table XII. 



TABLE XII 



Quicklime, 
Pounds. 


Water-slaked 
Lime, Pounds. 


Air-slaked 
Lime, Pounds. 


2000 


2643 


3571 



77. Applying Lime to the Soil. Some difficulty attends 
the distribution of quicklime on the soil, for it is necessary 



102 



CHEMISTRY OF FARM PRACTICE 



to slake it before it can be spread. This is often accom- 
plished by putting the material in small piles at regular 
intervals over the field and covering the piles with moist 
earth, which promptly water- slakes the lime, making it 




Fig. 35. — Effect of liming spinach. (R. I. Exp. Station.) 



into a powdered condition in which it may easily be spread 
from the piles. 

A number of State Experiment Stations have investi- 
gated the use of lime, in various forms, with the general 
conclusion that best results are obtained from the use of 
calcium carbonate. Results at the Pennsylvania Station, 
covering a period of over sixteen years, indicate that on 



AGRICULTURAL LIME 



103 



plots to which caustic lime (Ca(0H) 2 ) was applied as com- 
pared with the application of twice the quantity of ground 
limestone (CaCOs) there was a loss from the caustic lime, 
during that period, of 375 pounds of nitrogen, without a 
corresponding increase in yield. 

At the Rhode Island Station, it was found that Ken- 
tucky blue grass, timothy, awnless brome grass, meadow 
oat grass, tall fescue, and orchard grass were benefited, 




Fig. 36. — Distributing lime with a lime spreader. 
Ohio Exp. Station.) 



(Bulletin 159, 



while red top and Rhode Island bent did well without lime. 
Beets and spinach showed marked effects from liming, less 
marked effects being shown on rye, carrots, and crimson 
clover. The following plants were improved, due to appli- 
cation of lime: Strawberries, asparagus, rhubarb, white 
mustard, leeks, endive, mangel wurzels, muskmelons, dwarf 
brown corn, sweet peas, and poppies. Watermelons are 
greatly injured by applications of lime, and should not be 
planted on limed soil until three or four years have elapsed 



104 CHEMISTRY OF FARM PRACTICE 

since the application. Parsley and chicory show little 
benefits from liming. 

It is advisable to apply lime in autumn, preferably after 
a large amount of vegetable material has been turned 
under. The lime may be applied by means of machines 
especially constructed for the purpose, and should be 
spread as evenly over the surface of the soil as possible, 
and disk-harrowed in to the depth of about two inches. 

78. Machine for Applying Lime. The Ohio Station 
makes the following recommendation for constructing a 
home-made machine for the application of ground lime- 
stone. 

Make a hopper similar to that of an ordinary grain drill, measur- 
ing inside 8\ feet or 11 feet long with sides about 21 inches wide and 
about 20 inches apart at the top. The sides may be trussed with 
f-inch iron rods running from the bottom at the middle to the top 
at the ends of the hopper. Let the bottom be 5 inches wide in the 
clear, and cut in it crosswise a row of diamond-shaped holes, 2 inches 
wide, 2 1 inches long, and 4 inches apart (6 inches between centers). 
Make a second bottom with holes in it of the same size and shape 
as those of the main bottom, and so shaped that they will register. 
Let this second bottom slide loosely under the first, moving upon 
supports made by leaving a space for it above bands of strap iron 
12 inches apart, which should be carried from one side to the other 
under the hopper to strengthen it. The upper bottom piece may be 
made of about 8-inch sheet steel, and the lower one may be smooth, 
seasoned hard wood, about 1 inch thick and 7 inches wide, reinforced 
with strap iron if necessary, and well oiled or painted. To this under 
strip attach a V-shaped arm, extending an inch in front of the hopper, 
with a half-inch hole in the point of the V, in which drop the end 
of a strong lever, bolting the lever loosely but securely to the side 
of the hopper, and fasten to the top of the hopper a guide of strap 
iron, in which the lever may move freely back and forth. The object 
of this lever is to regulate the size of the openings by moving the 
bottom board. Make a frame for the hopper, with a tongue to it, 
similar to the frame of an ordinary grain drill. 

Get a pair of old mowing-machine wheels with strong ratchets 
in the hubs, and with pieces of round axle of sufficient length to pass 
through the frame and into the ends of the hopper, which are to be 
welded to a square bar of iron about If inches in diameter and the 



AGRICULTURAL LIME 105 

length of the inside of the hopper. The axles should be fitted with 
journals, bolted to the under side of the frame. 

Make a reel to work inside of the hopper by securing to the axle, 
12 inches apart, short arms of f-inch by 1-inch iron, and fastening 
to these arms four beaters of f-inch square iron, about an inch shorter 
than the inside of the hopper, the reel being so adjusted that the 
beaters will almost scrape the bottom of the hopper, but will revolve 
freely between the sides. The arms may be made of two pairs of 
pieces, bent so as to fit around the axle on opposite sides, and secured 
by small bolts passing through the ends and through the beater, 
which is held between them. The diameter of the completed reel 
is about 5 inches, and it serves as a force feed. 

Two pieces of oilcloth may be tacked to the bottom of the hopper, 
one in front and one behind, of sufficient width to reach nearly to the 
ground, in order to reduce the annoyance of the flying dust to man 
and team. Another piece may be buttoned across the top of the 
hopper in windy weather, if desired; but the dust of limestone or of 
natural phosphate is certainly no worse than the dust of the field. 

A sort of second force feed has been evolved from the extensive 
experience of Illinois farmers in building home-made machines: Two 
pieces of sheet steel, each about 6 inches wide and the length of the 
machine, are used as a V-shaped bottom for the hopper, forming nearly 
a right angle at the lowest point. One piece is stationary and the 
other is given an endwise motion back and forth by means of a small 
wheel with a heavy rim waving in and out horizontally and running 
through a slotted piece firmly attached to the movable sheet steel. 
Two very small wheels forming the sides of the slot serve to reduce 
the friction, and a lever is arranged to throw this mechanism out of 
gear. One of the pieces of sheet steel is provided with an adjustment 
by means of which a crack is opened of any desired width, the entire 
length of the bottom. Thus the stone falls, not through holes or 
in streaks, but in a perfect broadcast. Several of these home- made 
machines are in use. The draft is more than with the reel alone, but 
they are undoubtedly more satisfactory than anything on the market. 

The cash expense for such a machine, aside from the 
mower wheels with axle and ratchets, has varied from 
less than $10 to more than $20, depending on the cost of 
material and labor. Farmers with some mechanical skill 
hire only the necessary blacksmithing. 

79. Gypsum. Many soils, especially in the Southeastern 
part of the United States, have received by the applica- 



106 CHEMISTRY OF FARM PRACTICE 

tion of superphosphate fertilizer, a large quantity of gypsum 
(calcium sulphate). To make superphosphate, the ground 
phosphate rock is treated with sulphuric acid, the result 
of this action being a soluble calcium acid phosphate and 
gypsum in the proportion shown by the equation, 

Ca 3 (P0 4 )2+2H 2 S0 4 +5H 2 = 

2CaS0 4 • 2H 2 + CaH 4 (P0 4 ) 2 • H 2 0. 

Rock phosphate contains other calcium salts than phos- 
phate, such as the fluoride and carbonate, and these also 
appear as calcium sulphate after the action of the sul- 
phuric acid. Considerably over one-half, often 70 per cent, 
of superphosphate is gypsum. This, however, is no dis- 
advantage, for gypsum, when applied to leguminous crops 
for the calcium sulphate, releases potassium present in 
an insoluble condition in clay soils formed by the decom- 
position of feldspar rocks. 



CHAPTER XII 

PHOSPHORUS 

80. Presence in the Soil. Of all minerals necessary 
for plant growth the compounds containing phosphorus 
are most liable to be deficient. The average of many anal- 
yses of the earth's crust shows the presence of only y^ 
of 1 per cent of phosphorus, while many of our best arable 
soils contain considerably less than that amount. The 
phosphorus present in the soil is usually in the form of a 
calcium phosphate. Calcium, with its valence of two, and 
the phosphate radical, with its valence of three, unite in 
accordance with the criss-cross rule stated previously, so 
as to form normal calcium phosphate with the formula 
Ca3(PO)2. This is known in the trade as rock or bone 
phosphate. There are also two acid phosphates, the di- 
calcium phosphate Ca2H2(P04)2, known as reverted phos- 
phoric acid, and the mono-calcium phosphate, CaH^PO^, 
which, when mixed with calcium sulphate, is known as 
the superphosphate of lime. The reaction with sulphuric 
acid by which the insoluble rock phosphate is converted 
into the soluble superphosphate is as follows: 

Ca 3 (P04)2+2H 2 S04 = CaH4(P04)2+2CaS04. 

Should there not be enough sulphuric acid to complete 
this reaction, or, in other words, should there be excess of 
rock phosphate, the following reaction may take place : 

CaH4(P04)2+Ca3(P04)2 = 2Ca 2 H 2 (P04)2. 

Thus, there will be formed the reverted phosphate, which 
is insoluble in water. 

107 



108 CHEMISTRY OF FARM PRACTICE 

The inorganic phosphorus present in the soil is generally 
in the form of the normal calcium phosphate combined 
with fluorine and chlorine (Ca3(P04)2CaFCl), although 
some of it is found as the phosphates of iron or aluminium. 
Aluminium phosphate is a normal constituent of rock phos • 
phate, but phosphates containing iron, even in very small 
amounts, are rejected, as the iron has the power in the soil, 
even after the treatment with sulphuric acid, to take away 
phosphoric acid from acid phosphates and render them 
insoluble. A small amount of the total phosphorus of the 
soil is found combined in organic compounds and is liberated 
by the decay of organic matter. 

Experimental results have indicated that 1 per cent 
of the total phosphorus present in the soil is available 
during the course of a year. Obviously this availability 
will depend upon several factors, the form of combination 
of the phosphorus, the amount of soil moisture, the content 
of decaying organic matter, and the influence of added 
fertilizers on the solubility of the material present. It 
must be kept in mind that, in explanation of the low phos- 
phorus content of normal soils, a large per cent of the 
phosphorus used is stored in the seed of the plant, which 
is generally the product sold off the farm. Assuming 
x^o of one per cent of phosphorus and 2,000,000 pounds of 
soil in the surface area per acre, a total of only 1000 pounds 
of phosphorus will be present, of which perhaps 1 per 
cent will become available, furnishing 10 pounds of phos- 
phorus combined in soluble compounds. Ten pounds of 
soluble phosphorus, providing that none leached out, would 
furnish per acre phosphorus sufficient to make 43 bushels 
of corn, or 62 bushels of oats, or 31 bushels of wheat, or 
cotton sufficient to amount to 375 pounds of lint. As 
a matter of fact, many soils do not contain as much as 
ro-o of 1 per cent of phosphorus, and some of the available 
phosphorus is lost through leaching. 

81. Commercial Sources. The farmer has at his dis- 



PHOSPHORUS 



109 




03 



'8 

O 

o 
o3 



ft 

EC 

o 

■a 

bfi 



110 CHEMISTRY OF FARM PRACTICE 

posal a number of phosphorus-bearing materials to supply 
a deficiency of phosphorus in the soil. The materials de- 
rived from farm lands are animal manures, bones, and some 
vegetable products, such as cottonseed meal, which, while 
valued mainly for its nitrogen, contains a considerable 
amount of phosphorus. But the phosphorus in these ma- 
terials all came originally from the soil; so, by merely 
returning it, we cannot hope to keep up the normal supply. 
Animal manures do not contain enough phosphorus to 
make them a balanced fertilizer, hence it is desirable to 
add a certain amount of a phosphatic fertilizer- The 
same is true for cottonseed meal, rapeseed meal, and castor 
pomace, all of vegetable origin, when used in fertilizer. 
The most important commercial sources of phosphorus 
whereby the normal content of the soil may be main- 
tained are phosphate rock, superphosphate, bone, Thomas 
slag, mineral phosphate, and guano. 

82. Phosphate Rock. This is obtained from mineral 
deposits in the earth that are directly traceable to organic 
origin. The United States fortunately has large deposits 
of this rock. Those in Florida, Alabama, South Carolina, 
Tennessee, and Arkansas have produced enormous quan- 
tities of the rock. There are extensive deposits in Idaho, 
Utah and Wyoming which are not yet developed. Within 
the last decade considerable attention has been devoted 
to the use of finely ground phosphate rock as a source of 
phosphorus. Experiments have proved that this ground 
rock may profitably be used in connection with animal 
manures or an abundant supply of decaying organic matter 
derived from any source. When ground phosphate rock 
is purchased, it should be specified that 90 per cent of the 
material shall pass through a sieve having 100 meshes to 
the linear inch. It has been shown that when 50 to 100 
pounds of these " floats " are mixed with each ton of ani- 
mal manure, good results follow. It is advisable to get 
floats which are ground from unburned rock, for the burn- 



PHOSPHORUS 



111 




,13 






112 CHEMISTRY OF FARM PRACTICE 

ing drives off the combined water and makes the material 
less soluble. 

83. Acid Phosphate or Superphosphate. This is the 
form of phosphorus most used as a fertilizer. The reaction 
given on page 23 by which the insoluble phosphate rock 
is made soluble was discovered by Baron Liebig and was 
applied by him to the treatment of bones. About 1845, 
Lawes made use of this reaction for the treatment of the 
newly discovered mineral source of phosphorus, coprolite, 
and from this beginning the manufacture of phosphates 
has grown into an immense industry. Superphosphate 
should not be mixed with rock phosphate, lime, Thomas 
phosphate, cyanamid, or basic calcium nitrate, because the 
calcium contained in these materials would " revert " the 
acid salts of calcium phosphate into the insoluble dical- 
cium phosphate, in this way neutralizing the advantages 
of the acid treatment. A soluble phosphate, when applied to 
the soil, goes into solution in the soil water and is diffused 
throughout the soil. When it comes in contact with a 
basic material, it is precipitated in fine solid condition 
on the surface of the soil particles. In this way, the added 
phosphate is widely distributed, and the exudation from 
root hairs of the plant, coming in contact with it, dissolves 
the phosphate, which then by osmosis is taken into the 
plant structure. 

Acid phosphate applied together with fertilizer contain- 
ing nitrogen and potash gives the best results, the proper 
proportions for each case varying with the soil and the 
crop to be grown. In many cases, superphosphate, when 
applied alone, is advantageous, especially on land well 
supplied with organic matter. The fact that superphos- 
phate carries with it much sulphate of lime or land plaster 
should always be remembered in connection with the use 
of this phosphate as a fertilizer. Land plaster has the 
property of aiding in the breaking down of organic matter 
in the soil and of liberating potash and phosphorus from 



PHOSPHORUS 



113 





114 CHEMISTRY OF FARM PRACTICE 

insoluble compounds in the soil, in this way depleting in 
time the local supply. Land plaster acts similarly to 
lime, in that it may furnish calcium, an essential plant 
food element. It also assists in liberating nitrogen from 
organic compounds and also frees insoluble potash and 
phosphorus, but it does not correct acidity. 

84. Thomas Phosphate or Basic Slag. In the manu- 
facture of steel, various processes are resorted to for the 
purpose of removing the phosphorus from the pig-iron 
from which the steel is manufactured. Essentially all 
processes consist of lining the furnaces with dolomite, a 
calcium magnesium limestone, before the pig-iron is put 
in. The mass is subjected to a high heat, and the mag- 
nesium limestone slags off the phosphorus as calcium phos- 
phate, which rises to the surface. This slag is drawn off 
from the converter, cooled, broken, finely ground and placed 
on the market. It is stated that slag consists of trical- 
cium phosphate and calcium silicate in proportions shown 
by the formula (CaO)5P20sSi02. This material may con- 
tain some free lime, and more lime may become soluble 
by repeated washings. Thomas slag gives good results 
on sour lands that contain organic matter, on lands rich 
in humus, and on lands deficient in lime. It must not be 
mixed with any material containing salts of ammonia — 
for example, sulphate of ammonia — because the free lime 
will liberate the ammonia as a gas, which will be lost. 

85. Bone. Among the sources of phosphorus, both 
raw and steamed bone have held an important place. 
Raw bone contains 3 to 4 per cent of nitrogen in the form 
of organic matter, and from 20 to 25 per cent of phos- 
phoric acid. About half of this phosphoric acid is avail- 
able, more becoming available as the bone decays. The 
composition of the bone varies with the age of the animal, 
the bones of old animals usually containing more phos- 
phorus and less nitrogen. 

Bones are steamed for the purpose of removing the 



PHOSPHORUS 



115 



gelatine and glue. In this process, much of the nitrogenous 
material is removed; but, as the phosphoric acid is not 
removed to any extent, the decrease in weight of the 
bones caused by the materials extracted brings about a 
corresponding increase of the percentage of phosphoric 
acid. The process of extraction also removes the greases 




Fig. 40. — Corn grown without the use of special fertilizer. 



and fats which interfere with the decomposition of the raw 
bone in the soil. Experiments show that steamed bone 
acts more quickly and is more valuable as a source of 
phosphorus than raw bone. Raw bone is especially prized 
as a source of phosphorus and nitrogen for fruit trees, 
where a slowly available supply of these elements is desired. 
86. Mineral Phosphate. Deposits of mineral phosphates 
which are not derived directly from organic sources are 



116 



CHEMISTRY OF FARM PRACTICE 



widely distributed in rocks of igneous origin. A typical 
mineral phosphate is apatite, a double phosphate, and 
fluoride of calcium with the formula Ca3(PC>4)2-Ca2FPO*. 
Formerly large quantities of this mineral were imported 




Fig. 41. — Corn grown on the same area and soil as that of Fig. 40, 
with the addition of 500 lbs. acid phosphate and 188 lbs. dried 
blood per acre. 



from Canada for manufacture into fertilizer. The expense 
of mining and transportation does not permit this mineral 
to enter into competition with rock phosphate as a fertilizer. 
87. Guano. This material has been a rich source of 
phosphorus as well as of nitrogen. The standard Peruvian 



PHOSPHORUS 



117 



guano contains nearly 40 per cent of bone phosphate, 
corresponding to about 18 per cent of phosphoric acid 
(P2O5). Certain small, rocky islands of Peru, owing to 
the abundance of fish found in the waters of these coasts, 
have been the habitat for untold ages of enormous numbers 
of sea birds. Rain seldom falls in these regions and the 
excrement (Spanish Guano) has collected in thick deposits. 




Fig. 42. — Corn grown under the same conditions as that of Fig. 40, 
but with 160 lbs. of muriate of potash added per acre. 



From one group of these small islands, the Chincha, guano 
to the value of $1,000,000,000 has been taken. As a source 
of phosphorus guano is much more expensive than is rock 
phosphate and the supply is being exhausted. 

88. Purchase and Application of Phosphorus. The selec- 
tion of the source of phosphorus to use is largely an economic 
problem to be determined by the costs of the materials 
delivered on the farm. Lower prices for fertilizing ma- 



118 CHEMISTRY OF FARM PRACTICE 

terials are secured by buying them in car-load lots from 
the manufacturer or wholesaler. The author has known 
as great a difference as 60 per cent in cost between buying 
in car-load lots from the wholesaler and in buying in small 
quantities from the retailer. 

Experiments have been conducted to determine which 
source of phosphorus is most effective for the different 
crops on different soils, taking into account the cost of 
the material carrying the phosphorus. The results of these 
experiments agree that ground phosphate rock is the most 
economical source of phosphorus on the market. It has 
an additional advantage in that its content of phosphorus 
is higher than that of any other commercial source, thus 
enabling the purchaser to transport a large number of 
pounds of phosphorus in a ton of material. Its chief 
disadvantage lies in the fact that it is the most unavail- 
able source of commercial plant food. 

Ground phosphate rock can be used to advantage under 
two sets of conditions: 

(a) For sprinkling in stalls or barnyards where animal 
manures are accumulating. This addition of ground phos- 
phate rock should be made at intervals so that it will be- 
come thoroughly incorporated with the manure. It is 
advisable to add ground phosphate rock at the rate of 
from 50 to 100 pounds for each ton of manure accumulated, 
the quantity within these limits depending upon the total 
amount of manure to be applied per acre. If applications 
of more than 12 tons of manure per acre are to be made, 
50 pounds of ground phosphate rock per ton should suffice; 
if lighter applications of manure are to be made, 100 pounds 
per ton would be preferable. The thorough incorporation 
of the finely ground phosphate in the animal manure will 
subject a large surface area of that material to the action 
of the acids present in the manure, causing some of it to 
be converted into the more available forms. After the 
manure is applied to the field, the processes of nitrifica- 



PHOSPHORUS 119 

tion will cause further reactions to take place which grad- 
ually render the phosphorus available. 

(6) Ground phosphate rock can be used to advantage 
in a rotation which assures an abundant supply of decay- 
ing organic matter. Decaying organic matter is the key 
to profitable farming; few farmers realize when their soil 
has an abundance of this material. It is the general opinion 
that merely following a rotation will assure an abundance 
of organic matter; as a matter of fact, it is necessary that 
large crops be grown so that the crop residues will be large. 



CHAPTER XIII 

NITROGEN 

89. Importance of Nitrogen. The need of nitrogen in 
crop production cannot be over-emphasized. The lack of 
a plentiful supply of this element in the organic form will 
inevitably make land infertile. In the formation of the 
earth's crust, the addition of nitrogen must have been 
very gradual, the first probably being due to the oxidation 
of atmospheric nitrogen by electrical disturbances. This 
operation is still effective, and oxides of nitrogen and 
ammonia gas (NH3) in small amounts are washed down 
by rain water. Nitrogen from this source must have 
nourished the earliest forms of plant life, and the organic 
remains of these lower plant forms must have supplied the 
basis for our supply of organic nitrogen in the soil. Neces- 
sarily the accumulation of this supply required very long 
periods of time. 

When enough organic matter had accumulated to make 
possible the growth of legumes, the accumulation of nitro- 
gen probably became much more rapid, as these plants 
bear round their roots nodules which are the homes of 
colonies of a species of bacterium that have the power of 
causing the nitrogen and oxygen of the air to unite, thereby 
" fixing " the nitrogen. There are to-day many wild 
legumes still adding to the supply of nitrogen in an organic 
form. Therefore, the cultivation of domestic legumes, such 
as the clovers, cowpeas, vetches, alfalfa, field peas, beans, 
lupines, and peanuts cannot be urged too strongly. Certain 
sections of the United States make successful use of these 
crops in rotation, to furnish their nitrogen supply. For 
specialized crops, such as cotton, tobacco, sugar cane, 

120 



NITROGEN 



121 




pq 



b£ 



122 CHEMISTRY OF FARM PRACTICE 

sugar beets, and truck, it is necessary to make additional 
use of nitrogen derived from a commercial source. How- 
ever, it is recommended that the annual legumes be used 
as catch crops and cover crops to supplement the arti- 
ficial supply. 

It is an interesting fact, established experimentally by 
Lipman of New Jersey, that a non-leguminous crop grown 
as a companion crop with a legume may derive nitrogen 
from the supply of atmospheric nitrogen fixed by th? 
legume. The experiment was conducted as follows: A 
small glazed pot was placed in a large pot to serve as a 
check, while a small non-glazed pot was placed in another 
pot for the determination. All pots were filled with earth 
and a legume was planted in the outer pot in each case, 
and the non-legume in the inner pots. Where the non- 
porous inner pot was used, the non-legume made much 
poorer growth than where the porous inner pot was used, 
because the soluble nitrogen could go through the walls 
of the porous inner pot to serve to nourish the non-legume. 

90. Commercial Nitrogen Profitable. After supplying 
all nitrogen that it is practicable to secure by means of 
leguminous crops, it is still generally advisable to apply 
nitrogen in the commercial form to specialized, high-priced 
crops. The grower of early truck can afford to purchase 
a large amount of high-priced fertilizer if it will improve 
the quality, yield, and early maturity of his product. The 
same will hold true to a less extent with tobacco, sugar 
cane, sugar beets, and cotton. 

91. Selection of Source of Nitrogen. In purchasing 
nitrogen in its various forms, great care must be taken in 
the selection of the source to assure high agricultural value. 
As nitrogen is the highest priced element of commercial 
fertilizers, there are more attempts to palm off an inferior 
kind of nitrogenous fertilizer than in the cases of phos- 
phorus or potassium. It is usually unwise to buy low- 
grade fertilizers at any price; the best are cheapest in 



NITROGEN 



123 




124 CHEMISTRY OF FARM PRACTICE 

the end, and the reduction in price of the inferior sources 
is usually not great. 

The crop grown and the character of the soil should be 
the determining factors in the selection of the sources of 
nitrogen. Light sandy soils are leachy, and do not easily 
retain soluble plant food, therefore it is often advisable 
to make use of organic sources with such soils. Some 
crops have to be forced and require a large amount of 
rapidly available fertilizer; but these crops are usually so 
valuable that the grower can afford a certain amount of 
loss through leaching. 

92. Inorganic Sources of Nitrogen. The sources of 
nitrogen may be divided into two classes — organic and 
inorganic. The inorganic sources of the nitrogen found 
in commerce in large quantities are potassium nitrate, 
(KNO3), sodium nitrate (NaNOs), calcium nitrate (Ca(NOs)2) 
and sulphate of ammonia ((NFL^SC^). These are all 
easily soluble in water. The nitrates remain soluble under 
all conditions until they are either used as plant food, 
leached out, or, as occurs under very unusual conditions, 
lost through denitrification. The nitrates are so soluble 
that they may be considered the most thoroughly predi- 
gested nitrogenous plant food and, therefore, are most 
efficacious when applied to a growing crop as a topdressing. 
Sulphate of ammonia reacts with certain soil compounds 
which render the ammonium radical (NH 4 ) less soluble 
in water and, consequently, more slowly available. This 
reaction is supposed to take place between the ammonia 
salts and compounds in the soils called zeolites. The zeolites 
are double hydrated silicates of aluminium with some 
other base which is interchangeable. Examples of zeolites 
are Thomsonite, CaAl 2 Si20 8 , and natronite, Na2Al 2 Si30i . 
The bases that may be substituted in the zeolites are cal- 
cium, sodium, potassium, and ammonium. Sodium will 
displace calcium in the zeolitic compounds, while potas- 
sium will displace sodium or calcium, and ammonium will 



NITROGEN 



125 



displace potassium, sodium, or calcium. Ammonia salts 
are constantly forming in the soil; thus nature has fur- 
nished a means for their conservation if the nitrification 
is not rapid enough to take up the ammonia formed. The 
fact that the four basic materials enumerated above are 




Fig. 45.* — Blasting a test hole in caliche to obtain nitrate of soda. 



held in the relative order of their agricultural value is 
significant. 

There is another action which may cause calcium to 
liberate sodium, potassium, or ammonium; sodium to 

* Figs. 45-50 are furnished by The Nitrate of Soda Propaganda, 
William S Myers, Director. 



126 



CHEMISTRY OF FARM PRACTICE 



liberate potassium or ammonium; and potassium to liberate 
ammonium; the converse of the above. This is termed 
?nass action. When heavy applications of lime are made, 
mass action ensues and much stored up plant food is 
liberated. 

Certain salts have the power of absorbing water from 




Fig. 46. — Opening up a trench after blasting; 
by piece work. 



extraction of caliche 



the atmosphere. This property is termed deliquescence. 
A very deliquescent material may be hard to preserve 
in a good mechanical condition, as it may absorb enough 
moisture to become sticky or even to dissolve in the water 
taken in. 

93. Potassium Nitrate, " Niter," " Saltpeter." This 
salt is the least deliquescent of the three common commer- 
cial nitrates. It contains nitrogen and potassium both 



NITROGEN 127 

in comparatively large percentages. The pure salt, KN0 3 , 
contains nearly 14 per cent of nitrogen, and over 41 per 
cent of potassium oxide. In commerce, the percentages 
run 1 or 2 per cent lower than these figures. Potassium 
nitrate is extensively mined in India; but there is a large 
demand for it in the arts, especially for the manufacture 



*JM 



. * -Air-'*" '*">> 



"XT* 




Fig. 47. — Loading caliche on railway trucks. 

of gunpowder, consequently the cost is so high that little 
finds its way into the fertilizer trade. Potash salts from 
the Stassfurt deposits in Germany have been the chief 
sources of potassium, but other compounds containing 
nitrogen are much cheaper sources of that element than is 
potassium nitrate. 

94. Sodium Nitrate, " Chili Saltpeter," " Soda Salt- 
peter." Deposits of sodium nitrate (NaNOs) are found 



128 CHEMISTRY OF FARM PRACTICE 

generally in the soils of arid or semi-arid regions, but only 
in a few regions is there a percentage high enough to war- 
rant their leaching and purification. Very extensive de- 
posits are located on the western coast of South America, 
principally in Chili, whose government derives a large 
income from this source. The deposit is called caliche, 




Fig. 48. — General view of crystallizing pans for obtaining nitrate of 
soda. Each pan has about 500 cu. ft. capacity and 225 sq. ft. 
cooling surface. 

and occurs at depths ranging from 10 inches to 16 feet from 
the surface of the soil. The layers containing the sodium 
nitrate vary in thickness from 6 inches to 3 feet. This 
material is generally covered with a kind of conglomerate 
rock called costra. These beds are from 15 to 90 miles 
distant from the sea-coast and extend 220 miles in length 
and in some places 2 miles in breadth. It is believed that 



NITROGEN 



129 



they were formed comparatively recently and are due 
to the nitrification of marine vegetation; that continued 
teachings from soils accumulated in great lakes in which 
much vegetable material grew and accumulated; and that 
finally these lakes became isolated, and evaporation and 
rapid nitrification took place. The presence of iodine in 




Fig. 49. — Deposit of nitrate crystals in the pans of Fig. 48 after the 
liquor is run off. 

the caliche would seem to support the theory of marine 
formation. There are a number of impurities in the natural 
sodium nitrate, among which are organic matter, common 
salt, calcium sulphate, and insoluble silica. 

Some niter deposits have been found in California, 
though these are not of so high grade as those of Chili. 
An average of more than a hundred analyses of these Cali- 



130 



CHEMISTRY OF FARM PRACTICE 



fornia claims shows a sodium nitrate content of about 
9| per cent. The low niter content and poor transpor- 
tation facilities have prevented the development of these 
deposits. About 1,750,000 tons of nitrate of soda, con- 
taining about 15§ per cent nitrogen, are annually shipped 
out of Chili, about one-tenth of which comes direct to 




Fig. 50. — Drying floors and bagging of nitrate of soda. 



the United States. Some of the European supply is also 
reshipped to this country. 

95. Calcium Nitrate. After many unsuccessful attempts 
the compound, calcium nitrate, is now manufactured com- 
mercially in this country and abroad from nitrogen of 
the atmosphere by electrolytic means. In Notodden, Nor- 
way, where the large water-power is utilized to produce 



NITROGEN 131 

electric energy, three factories have been established, where, 
in 1911, there was manufactured calcium nitrate to the 
value of $350,000. Air at the rate of 25,000 liters per 
minute is sent through the electric arcs spread by powerful 
electro magnet. About 1 per cent of the total volume of 
gas is oxidized to nitric oxide (NO). This oxide leaves the 
apparatus through a tube kept at a temperature of 500-700° 
Centigrade; the gases are then rapidly cooled to 50-60° 
C, a temperature favorable to the further oxidation of 
the nitric oxide to nitrogen tetroxide (NO2). This product 
reacts with water to produce nitric and nitrous acids. 
The equation expressing this reaction is 

2N0 2 + H 2 = HNO3 + HN0 2 . 

The nitric products that fail to be absorbed in the water 
are caught in a milk of lime trap as calcium nitrate and 
calcium nitrite. The latter is liberated as nitrous oxide 
by treating with nitric acid. The reaction is 

Ca(N0 2 )2+2HN03 = 2HN02+Ca(N0 3 )2. 

The nitrous oxide is again put through the process of con- 
version into nitric acid. At least 95 per cent of the oxide 
of nitrogen formed is transformed into nitric acid of 50 
per cent strength. The nitric acid is converted into nitrate 
of lime by adding it to the correct quantity of calcium 
carbonate, according to the reaction 

2HN0 3 +CaC03 = Ca(N03)2+C02+H 2 0. 

The nitrate of lime formed is 75 to 80 per cent pure, and 
contains about 13 per cent of nitrogen. This material 
must be shipped in casks on account of its deliquescence. 
The deliquescence of normal calcium nitrate has led to 
the manufacture of some basic nitrate of lime, which is 
accomplished by the addition of the proper amount of 
quicklime to the hot solution. The equation is 

CaO+Ca(N0 3 )2 = Ca 2 0(N0 3 )2. 



132 CHEMISTRY OF FARM PRACTICE 

Basic calcium nitrate contains about 10 per cent of 
nitrogen. 

96. Ammonium Sulphate. This material is a by-prod- 
uct of the gas-works, bone distilleries, and coke-ovens. It 
contains about 24 per cent of ammonia, and is soluble in 
water. Its action in the soil has already been discussed. 
It is a good source of nitrogen for plant food, but it is 
higher in price than is nitrate of soda. 

97. Organic Sources of Nitrogen. The organic com- 
pounds containing nitrogen vary greatly in their agri- 
cultural value. 

Animal Sources: (a) Dried blood is a by-product of 
the slaughter-houses. It is carefully saved, because of 
its high value as a source of nitrogen. The fresh blood 
contains about 2J per cent of nitrogen, but, after drying, 
the product contains from 12 to 14 per cent. Blood is 
an excellent quickly available source of nitrogen for use 
on sandy land, and is highly prized as a source of nitro- 
gen for sugar cane and tobacco. It nitrifies much more 
rapidly than the other organic forms of nitrogen. 

(6) Dried ground fish is an important source and con- 
tains from 7 to 10 per cent of nitrogen, and usually from 
6 to 9 per cent, of total phosphoric acid. This material is 
obtained as a mixture of refuse and whole fish from the 
herring, pilchard, and mackerel fisheries. Fish has long 
been used as a fertilizer. The first colonists found the 
Indians using it as a fertilizer for corn. Fish is more 
slowly available than blood, and consequently more lasting 
in its effects. This fact enforces the importance of using 
at least two sources of nitrogen on farm crops having a 
long growing season. 

(c) Tankage. This term, variously modified, is employed 
to designate quite a range of fertilizing materials, and the 
modifying words should be carefully noted. There is a 
great difference between first-class slaughter tankage, con- 
sisting of the waste products of slaughter-houses, such as 



NITROGEN 133 

blood, flesh, and bone, and leather tankage which may 
consist of leather scraps which have not been chemically- 
treated to render them available. Considering the fact 
that, in the manufacture of leather, the hide is chemically 
treated to make it resistant to decomposition, it can readily 
be seen that untreated leather will be one of the last ma- 
terials to nitrify. Leather tankage is useless without 
treatment with sulphuric acid, but where so treated its 
nitrogen is available. Great care should be exercised to 
ascertain its value to the soil before purchasing any kind 
of leather tankage. 

(d) Peruvian guano consists of the excrement and car- 
casses of sea-fowls. It contains high percentages of both 
phosphoric acid and nitrogen, as well as some potash; 
but its chief value is due to its nitrogen content. Its source 
was noted when it was considered as a source of phos- 
phorus. It needs no treatment before applying. Fresh 
guano collected from some islands of the Pacific Ocean 
contains a considerable amount of ammonium carbonate 
and must be treated with sulphuric acid to fix this ammonia 
in the form of a sulphate, because the carbonate is very 
volatile. 

(e) Hoof meal should be classed apart from hides, horns, 
hair, and feathers. Hoof meal runs to about 14 or 15 
per cent of nitrogen, and it gives good results in field tests. 
The chemical methods for determining availability as plant 
food do not, as a rule, show the real value of this material. 

(/) Hides, horns, hair, and feathers are very resistant 
to nitrification, and hence they are of low agricultural value 
unless treatment with sulphuric acid is used to render 
the nitrogen available. These materials all run high in 
nitrogen content, but their use, when they cost much, is 
unadvisable. 

(g) Wool contains about 17 per cent of nitrogen. In 
uncleaned wool there is a fatty material known as suint, 
which contains a large per cent of potash salts, mainly in 



134 CHEMISTRY OF FARM PRACTICE 

the carbonate form, although some chloride and sulphate 
are present. In the wool of British sheep there is about 
10 per cent of potash salts. Wool is, also, very resistant 
to nitrification. 

(h) Bone. Raw and steamed bone have been discussed 
under sources of phosphorus. 

98. Vegetable Sources, (a) Cottonseed meal is the most 
important source of nitrogen of vegetable origin. It is 
very highly prized as a feed for animals on account of its 
high protein content, and can be used to greater advantage 
as a feed than as a fertilizer, provided that the manure 
is carefully conserved. It is much used in mixed fer- 
tilizers, not only on account of the plant food that it con- 
tains, but on account of the fact that it is an excellent 
material to keep moisture from salts which might absorb 
it. Cottonseed meal contains about 2 per cent of avail- 
able phosphoric acid, 6 per cent of nitrogen, and 1| per 
cent of water-soluble potash. 

(b) Rape meal is sometimes used as a fertilizer. It 
contains about 5 per cent of nitrogen and 1^% per cent 
of phosphoric acid. This meal is the product left after 
the removal of the oil from rape seed. It is finely ground 
before being marketed. 

(c) Linseed meal is a by-product of the manufacture of 
oil from flaxseed. The old process linseed meal is the 
residue left after pressing the oil out of the crushed flax- 
seed, either when cold or when warm. The linseed meal 
manufactured by the new process consists of the residue 
left after extracting the oil with naphtha. Linseed meal 
obtained by either process contains about 5| per cent of 
nitrogen, 1^ per cent of phosphoric acid, and 1J per cent 
potash. Linseed meal is mainly used as a feed for cattle. 

{d) Castor pomace is the residue left from the extraction 
of castor oil from the castor bean. It cannot be used as 
a stock feed on account of poisonous properties; but it 
has value as a fertilizer. It contains about 5| per cent 



NITROGEN 135 

nitrogen, If per cent phosphoric acid, and 1 per cent 
potash. 

(e) Calcium cyanamide is a manufactured organic source 
of nitrogen. It is a dark crystalline powder which, when 
exposed to the air, increases in weight, due to the slaking 
of the lime. This results in a lessening of the per cent of 
nitrogen that it contains, not by losing its nitrogen, but 
because of the increased weight of the product. 

Calcium cyanamide is manufactured by heating a mix- 
ture of limestone and coke in an electric furnace to a tem- 
perature of 1100° C. At this temperature calcium and 
carbon unite to form carbide (CaC2). The finely powdered 
calcium carbide has purified nitrogen gas passed over it 
when it is at a white heat and under these conditions it 
will take up two atoms of nitrogen according to the fol- 
lowing formula: 

CaC2+N 2 = CaCN 2 +C. 

The nitrogen of the air is purified either by passing it 
over red-hot metallic copper or by the fractional distilla- 
tion of liquid air. The manufactured product contains as 
impurities carbon, quicklime, silica, iron oxide, and cal- 
cium sulphide, phosphide and carbonate. It contains about 
20 per cent nitrogen, which is equivalent to 57 per cent of 
calcium cyanamide. 

The impurities in cyanamide, consisting of small quan- 
tities of sulphides, carbides, and phosphides, are decom- 
posed by the soil moisture when applied, and, unless suf- 
ficient time elapses for the escape of these products of 
decomposition that are harmful, the germination of seed 
is affected. The American Cyanamide Company claims 
that they have an improved process whereby the injurious 
impurities are removed. Their product is known as " Im- 
proved Cyanamide," and the nitrogen is present partly as 
the cyanamides of calcium and sodium, and partly as 
nitrate of soda. The American Fertilizer Handbook of 



136 CHEMISTRY OF FARM PRACTICE 

1910 gives a proximate analysis of this material, which 
shows 3.39 per cent nitrogen in the form of nitrate, and 
13.62 per cent of nitrogen in the cyanamide form. 

Experiments show that cyanamides do not give as good 
results as a fertilizer as does sulphate of ammonia, on 
soils containing an abundant supply of calcium carbonate. 
On acid soils, the lime content of the cyanamide should 
exert a good influence. 



CHAPTER XIV 

SOURCES AND USE OF POTASH SALTS 

99. Occurrence. Potassium is one of the ten elements 
absolutely essential to plant growth. Some crops are es- 
pecially heavy feeders on this element, prominent among 
them being the legumes, the root crops, the sugar-pro- 
ducing crops, and tobacco. Any crop is particularly sen- 
sitive to a deficiency of potash. 

The main commercial sources of potash salts are the 
Stassfurt deposits. These deposits are located in Saxony, 
Germany, and extend eastward from the Harz Mountains 
to the Elbe River about 60 miles, and from the city of 
Magdeburg southward to the town of Bernburg about 
20 miles. The deposits of these salts in this region are amply 
sufficient to supply the world for many centuries. 

These deposits are the result of the evaporation of 
an ancient inland sea which became isolated from the 
ocean. During the time of this evaporation, the climate 
of the section in question is supposed to have been trop- 
ical. As the evaporation continued, various salts crys- 
tallized out in the order of their insolubility. The lowest 
stratum consists of sulphate of lime, CaSCU; the next 
stratum consists of rock salt, which in places reaches a 
thickness of 3000 feet; the third stratum is the mineral, 
which consists of sulphate of lime, potash, and magnesia. 
Above this stratum comes the kieserit region, where there 
is a layer of sulphate of magnesia, and upon it rests a 
deposit of carnallite, which is a mixture of potassium chloride 
and magnesium chloride. The carnallite deposit varies in 
thickness from 50 to 130 feet. This deposit yields most 
of the crude potash from which the more concentrated 

137 



138 



CHEMISTRY OF FARM PRACTICE 



salts are produced. Kainit and sylvinit are found in adja- 
cent deposits. The kainit consists mainly of potassium 



v. 





' **■** .j -IN. 



a£* 



ft 



m 

4 
I 



Mi 




sulphate, magnesium sulphate, magnesium chloride, and 
sodium chloride, along with small quantities of potassium 



SOURCES AND USE OF POTASH SALTS 139 





Fig. 52. — Individual cotton stalk grown without special fertilizer. 



140 CHEMISTRY OF FARM PRACTICE 

chloride and calcium sulphate. Sylvinit consists mainly of 
potassium chloride and sodium chloride. Overlying the 
potash region is a layer of impervious clay, which has 
served to keep out water and prevent the loss of these 
salts by leaching. Above this clay are the following strata: 
anhydrite, gypsum, clay, sand, and limestone. 

The value of these salts was discovered about 1860, 
the potash salts having formerly been bored through and 
discarded as worthless, while the rock salt below was mined. 
Since the discovery of the value of these salts, the mining 
of them has been regulated by the German Government, 
which derives a large income from the export tax which is 
imposed. 

100. Wood Ashes. Before the discovery of the Stassfurt 
potash deposits, the main source of potash was wood 
ashes. The potash content of these ashes is in the car- 
bonate and sulphate forms. Ashes also contain a con- 
siderable percentage of lime, and a small percentage of 
phosphorus. Ashes from hardwood trees are higher in 
their potash content than other ashes. In conserving 
ashes for their potash content, they should be stored in 
a covered pit with impervious sides and floor, for the potash 
is readily leached out. 

101. Organic Sources of Potash. Some organic materials 
contain appreciable amounts of potash. Tobacco stalks 
and stems contain from 4 to 8 per cent of potash. Cotton- 
seed and flaxseed each contain some potash. Cottonseed 
contains about 1J per cent of potash, cottonseed meal about 
1| per cent, cottonseed hulls about 1 per cent, and cotton- 
seed hull ashes about 24 per cent. Linseed meal contains 
about If per cent potash. 

The pomace obtained from the fermenting of wine 
contains some potash and some nitrogen. 

102. Minor Sources. Another source of potash is kelp, 
the ashes of seaweeds. Kelp contains from 4 to 20 per 
cent of potash, depending upon the seaweed burned. 



SOURCES AND USE OF POTASH SALTS 141 




Pig. 53. — Cotton stalk grown in same soil as that of Fig. 52, fertilized 
with phosphoric add and nitrogen. 



142 



CHEMISTRY OF FARM PRACTICE 




Fig. 54. — Cotton stalk grown in same soil as that of Fig. 52, fertilized 
with phosphoric acid, nitrogen and potash. 



SOURCES AND USE OF POTASH SALTS 



143 



An inorganic source of potash that seems to offer some 
possibilities is the mineral alunite, which exists in large 
deposits in some of our western States. This material 
contains aluminium sulphate and potassium sulphate, and, 
when burned, the aluminium sulphate is decomposed, 
leaving alumina, which is insoluble in hot water, while 




Fig. 55.— Sweet potatoes grown without fertilizer. 

potassium sulphate is quite soluble and can be removed 
by lixiviation. 

At the prices that have formerly prevailed, the Stass- 
furt salts have crowded the other sources out of the gen- 
eral market. 

103. Commercial Salts of Potash. Two of these salts, 
kainit and sylvinit, already mentioned in Sec. 99, are 
exported and sold in the crude state. Kainit is a crys- 
talline gray material with some red and yellow particles. 



144 



CHEMISTRY OF FARM PRACTICE 



It contains, as a rule, between 12 and 13 per cent of 
potash (K2O). Sylvinit is similar in appearance to kainit; 
but it is redder in color. It is someties sold as kainit, 
and contains a slightly higher percentage of potash, rang- 
ing from 12| to 15 per cent of potassium oxide (K2O). 
The disadvantage in the use of these salts is that they 




Fig. 56. — Sweet potatoes grown on same soil as those of Fig. 55 but 
fertilized with phosphoric acid and nitrogen. 



are more expensive per pound of potash delivered on the 
farm than the purified salts. This is due to the fact that 
the transportation charges on a pound of potash in the 
form of kainit are four times those on the same amount 
of potash in the form of muriate of potash, because kainit 
contains 12 to 13 per cent potash, while muriate contains 
from 48 to 52 per cent. 

The purified potash salts on our market are muriate 



SOURCES AND USE OF POTASH SALTS 



145 



of potash, sulphate of potash, double sulphate of potas- 
sium and magnesium, double manure salts, and potas- 
sium-magnesium carbonate. 

104. The Functions of Potash. Potash in the soil 
favors the formation of the carbohydrates, such as starches, 
sugars, and cellulose in the plant. It is very beneficial 




Fig. 57. — Sweet potatoes grown on the same soil as those of Fig. 55 
but fertilized with potash, phosphoric acid and nitrogen. 



to such root crops as mangolds, sugar-beets, Irish potatoes, 
and sweet potatoes. It produces marked influences on the 
growth of leguminous crops, not only with respect to 
yield, but also with respect to the relative proportion 
of the legume to the other herbage. Potash induces the 
healthy development of the leaf and the stalk, and is 
especially beneficial to grasses. When applied in large 
quantities, potash lengthens the growing season of the 



146 CHEMISTRY OF FARM PRACTICE 

plant. It also seems to promote a more economical use 
of the soil moisture. 

105. The Use of Potash on Different Soils. The potash 
content of soils is very variable, ranging from T V of 1 per 
cent on very light sandy soils, to as much as 2 per cent on 
very heavy clay soils. 

The muck soils are very deficient in potash. Truck crops 
and practically all crops grown on light sandy and muck 
soils are improved by applications of potash salts. This is 
true to a very marked extent with cotton. On muck soils, 
the yields of corn are largely increased by the use of potash 
salts. In fertilizing general farm crops, unless there is some 
special reason that makes it objectionable, the use of muriate 
of potash is quite satisfactory and most economical. 

Heavy clay soils contain a sufficient supply of potash for 
general farm crops, and, if these soils are properly farmed so 
that the conditions for bringing stored up plant food into 
availability are accentuated, there should be such an 
abundant supply of potash that it will not become a limiting 
factor of plant growth. In fact, field tests show that large 
amounts of money are expended unnecessarily each year 
for the application of potash to such soils. 

Table XIII shows the effect of the use of potash on grass 
lands. The yield of hay is greatly increased and the growth 
of leguminous plants stimulated while the percentage of 
weeds is markedly decreased through the use of a com- 
plete mineral manure as compared with results obtained with 
a fertilizer not containing potash or with no fertilizer at all. 

106. Selection of the Source of Potash. The cheapest 
form of potash for sale in the United States is the muriate 
(KC1). This is manufactured by the purification of crude 
salts, most of the impurities being removed. While muriate 
of potash is a cheap and effective source for general farm 
crops, the use of a potash salt containing chlorine injures 
the burning qualities of tobacco, lowers the starch content 
of Irish and sweet potatoes, and hinders the crystallization 



SOURCES AND USE OF POTASH SALTS 



147 




148 



CHEMISTRY OF FARM PRACTICE 



TABLE XIII.— INFLUENCE OF POTASH ON GRASS LANDS. 

(Hall) 





Manuring. 


Dry Hay. 


Composition of Herbage 
in 1902. 


Plot. 


1856 

to 
1902 


1893 

to 
1902 


Grasses. 


^ Legu- 
"minous 
Plants. 


Weeds. 


7 


Complete mineral man- 
ure 


Cwta. 

38.8 

28.1 
23.3 
21.9 


Cwts. 

36.5 

21.6 

17.8 
15.9 


Per Cent. 

20.3 

28.8 
54.4 
34.3 


Per Ct. 

55.3 

22.1 

15.4 

7.5 


Per Ct. 

24.4 


8 

4 
3 


Complete mineral man- 
ure without potash. . . 
Superphosphate only . . . 
Unmanured 


49.1 
30.2 

58.2 









of the sugar contained in sugar beets. Sulphate of potash, 
double sulphate of potassium and magnesium, or potassium- 
magnesium carbonate should be used for the crops named. 
Truckers observe that when potatoes are fertilized with 
potassium sulphate, they are smoother than when fertilized 
with a salt of potash carrying chlorine. It has been shown 
at the South Carolina Experiment Station that the water 
content of sweet potatoes is higher when fertilized with 
muriate of potash than when fertilized with sulphate of 
potash. 

Double sulphate of potassium and magnesium is not ex- 
tensively used in the United States. It contains about 
26 per cent of potash, and may be used as a substitute for 
sulphate of potash. 

Double manure salts contain from 20 to 30 per cent of 
potash. It is used to some extent in the United States. 
The potash is mainly in the form of a chloride, and sells, 
usually, for more than does an equal amount of potash in 
kainit or in muriate of potash. 

Potassium-magnesium carbonate is a dry, white material 
containing from 20 to 25 per cent of potash combined as a 
carbonate. It is highly prized by growers of tobacco and 



SOURCES AND USE OF POTASH SALTS 



149 



K (& 



■/ 



1% s~ -•■ 



- v 



* 






"IB 


nB EL 




tRIHb" '■ - 




if 







150 



CHEMISTRY OF FARM PRACTICE 




•■a 
c 

a 

12 
'C 
o3 

_c 

o 

CO 

O 

a 



& 



SOURCES AND USE OF POTASH SALTS 151 

oranges. It is not deliquescent and, hence, is easily dis- 
tributed. 

In connection with the use of commercial potash salts 
it is interesting to note that plants take up a large part 
of their food, especially in the form of potassium and phos- 
phorus, and store it in the early stages of development ; while 
nitrogen is taken up, and carbonaceous material, such as 
starches and sugars, is for the most part formed in the later 
stages of the plants' development. This emphasizes the 
importance of applying the potash salts and the phos- 
phorus-bearing fertilizers before planting the crop, and the 
soluble nitrogen as a topclressing. 

107. Tendency to use too much Potash. It is also inter- 
esting to remember that most of the potash is stored in the 
leaves and the stalks of the plant, and, if these materials 
are incorporated in the soil or fed on the farm and the man- 
ure carefully conserved and returned to the soil, there will 
be comparatively a small loss of potash from the soil, 
although the plant makes use of more of it than of any other 
ash element. This fact, and the high content of potash 
present in most soils, shows that in many sections the 
application of commercial potash is largely over-done. To 
judge his potash needs accurately the farmer must thor- 
oughly understand the functions of potash, the composition 
and condition of his soil, and the requirements of the crops 
that he is growing. There is no element that pays so hand- 
somefy when needed or is so valueless when unnecessarily 
applied. 



CHAPTER XV 
MEASURING PLANT FOOD REQUIREMENTS 

108. Forms of Plant Food. There are two forms of 
each element of plant food present in every soil : the insolu- 
ble, or unavailable; and the soluble, or available. The 
former may be termed the potential plant food, and the 
latter the kinetic. The amount of available plant food is 
the limiting factor of plant growth, however much potential 
plant food may be present. The unavailable plant food is 
by natural processes slowly changed chemically so as to 
become soluble and these changes ma}^ be hastened by 
appropriate treatment. The depletion of the total food 
content of the soil must be avoided by application of fertilizer. 

109. Soil Analyses. The plant food in the soil is present 
in salts, minerals, and organic matter, which vary to a marked 
extent in their solubility in different solvents. The fact 
that solvents in the soil vary in their composition and 
therefore in their solvent power makes it extremely difficult 
to select a chemical solvent that truly represents the solvent 
power of the soil solvents; hence it is practically impossible 
to determine accurately by chemical means the absolute 
amount of available plant food in any soil. Soil analyses 
can only determine what elements are present, in what 
form and in what amount. They are suggestive of the 
treatment that should be given the soil and, therefore, in 
many ways are of value; but it should be remembered that 
soil analyses do not afford definite data of the amounts of 
various kinds of food plants may obtain. 

Hopkins' " Soil Fertility and Permanent Agriculture " 
estimates that, by the most approved agricultural methods, 
2 per cent of the total nitrogen content, 1 per cent of the 

152 



MEASURING PLANT FOOD REQUIREMENTS 153 

phosphorus content, and one-fourth of 1 per cent of the 
potash content of the soil generally can be made available 
in one year. If we have an analysis of the soil, we can 
readily calculate the number of pounds of each element of 
plant food that would become available, and if the com- 
position of the crop to be grown is known, the limiting 
factors of crop raising can be determined with some degree 
of accuracy, provided that the premises are correct and that 
unusual seasons do not exercise undue influence. 

110. Methods of Soil Analysis, (a) Collecting and Preparing Sam- 
ples for Analysis. A soil sample is collected by taking fifteen or twenty 
borings at different and apparently representative places on the soil. 
The borings should be dried, pulverized if necessary, and thoroughly 
mixed and rolled on a large piece of wrapping paper or enamel cloth; 
then by means of a spatula or wooden paddle, quarter the mass into 
four approximately equal parts, discard two-quarters that are diagonal 
to each other and continue the mixing, quartering and discarding until 
the residue amounts to about a pint. This residue should be an accurate 
sample of the field. A 2-inch auger with a long stem makes a good 
implement for collecting soil samples. Taken to a depth of 6f inches, 
an average soil weighs 2,000,000 pounds per acre, and taking the 
sample to this depth facilitates calculations. 

After air-drying, the sample is pulverized to pass through a sieve 
with round holes 1 millimeter or J^ of an inch in diameter. The gravel 
particles which are too large to pass through are weighed to determine 
the per cent present and then discarded. The sample is thoroughly 
mixed and placed in an air-tight container for analysis. The obtain- 
ing of a sample which fairly represents the soil is of the utmost im- 
portance, and time and care in this process are necessary. 

(6) Acidity or Alkalinity. Ten grams of soil are shaken with 100 
cubic centimeters of distilled water in a suitable flask and allowed to 
stand over night. The liquid is then decanted through a filter paper 
and 50 cubic centimeters are placed in a beaker, 2 or 3 drops of phenol- 
phthalein added, the beaker covered with a watch-glass and boiled to 
a volume of 5 cubic centimeters unless a pink color appears before that 
degree of concentration. If no color appears the soil is neutral or acid, 
while if a pink color appears it is evidence that the soil is alkaline. 

A very simple test for the reaction of a soil may be made by plac- 
ing a strip of blue litmus paper and a strip of red litmus paper in the 
bottom of a tumbler, adding the soil to be tested to a depth of about 
1 inch in the tumbler and then moistening the soil with either dis- 



154 CHEMISTRY OF FARM PRACTICE 

tilled water or rain water. At the end of an hour examine the paper 
by looking at the bottom of the tumbler. If both papers are red, 
the soil is acid; if both are blue, it is alkaline, and, if unchanged, the 
soil is neutral. 

(c) Phosphorus. The following provisional method for determining 
the phosphorus present is given together with some explanation on 
page 234, Bulletin 107 (revised) Bureau of Chemistry. Weigh 10 
grams of sodium peroxide into an iron or porcelain crucible and thor- 
oughly mix with it 5 grams of the soil. If the soil is very low in organic 
matter, add a little starch to hasten the oxidation action. Heat the 
mixture carefully by applying the flame of a Bunsen burner directly 
upon the surface of the charge and the sides of the crucible until the 
action starts. Quickly cover the crucible until the reaction is over 
and keep at a low red heat for fifteen minutes. Do not allow fusion 
to take place. By means of a large funnel and a stream of hot water, 
transfer the charge now free from organic matter to a 500 cubic centi- 
meter graduated flask. Acidify with hydrochloric acid and boil. Let 
cool and make up to the mark with distilled water. If the action has 
taken place properly, therd should be no particles of undecomposed 
or colored soil in the bottom of the flask. Allow the silica to settle 
and draw off 200 cubic centimeters of the clear solution. 

Precipitate the iron, alumina, and phosphorus with ammonium 
hydroxide added in slight excess to the warm solution, heat, stir, 
filter and wash several times with hot water, discarding the filtrate. 
Return the precipitate to the beaker with a stream of hot water, hold- 
ing the inverted funnel over the beaker, retaining the filter paper in 
the funnel, and dissolve the precipitate in hot hydrochloric acid, pour- 
ing acid upon the filter to dissolve any precipitate remaining and add 
this acid washing to the dissolved precipitate. Evaporate the solu- 
tion and washings to complete dryness on a water bath to dehydrate 
the silica. Take up with dilute hydrochloric acid, heating if necessary, 
and filter out the silica. Evaporate the filtrate and washings to about 
10 cubic centimeters, add 2 cubic centimeters of concentrated nitric 
acid, and just neutralize with ammonium hydroxide. Clear up with 
nitric acid, avoiding an excess. Heat at 40 to 50° on a water bath, 
add 15 cubic centimeters of molybdic solution, keeping at this temper- 
ature for from one to two hours. The molybdic solution is made an 
follows: Dissolve 100 grams of molybdic acid in 417 cubic centimeters 
of ammonia sp. gr. .96 and pour the solution slowly into 1250 cubic 
centimeters of nitric acid sp. gr. 1.20, keep the mixture in warm place 
for several days or until a portion heated to 40° C. deposits no yellow 
precipitate. Decant the solution for any sediment. Let stand 
over night, filter, and wash free of acid with a y 1 ^ per cent solution of 



MEASURING PLANT FOOD REQUIREMENTS 155 

ammonium nitrate and, finally, once or twice with cold water. Trans- 
fer the filter to a beaker, and dissolve in standard potassium hydroxide 
(1 cubic centimeter-0.2 milligram P), titrate the excess of potassium 
hydroxide with standard nitric acid of the same concentration as the 
KOH solution, using 0.5 cubic centimeter of phenolphthalein as in- 
dicator. Subtract the number of cubic centimeters of acid used from 
the cubic centimeters of KOH used, and multiply the remainder by 
.0002 and the result will be the grams of phosphorus present in 200 cubic 
centimeters of the soil solution. Determine the amount present in 
500 cubic centimeters, and dividing by the weight of soil taken for 
analysis (5), multiplying by 100 will give the per cent of phosphorus 
present. 

(d) Nitrogen. Seven grams of soil are weighed into a large Kjel- 
dahl flask, 0.7 gram of mercuric oxide is added, and to this is added 
about 20 cubic centimeters of cone, sulphuric acid. The contents 
of the flask are boiled and digested until colorless. Finely powdered 
potassium permanganate is added while the contents of the flask are 
hot, until a green solution furnishes assurance that the oxidation is 
complete. After cooling, about 250 cubic centimeters of water are 
cautiously added, then enough potassium sulfide solution to pre- 
cipitate out the mercury, and some zinc filings to lessen the bumping 
on boiling. Enough strong alkali is then added to neutralize the acid 
and leave the solution strongly alkaline. The flask is immediately 
connected to a still and the ammonia distilled off into a standard 
solution of sulphuric acid. The excess of acid is titrated with standard 
sodium hydroxide solution of the same concentration as the sulphuric 
acid, using an alcoholic extract of cochineal as an indicator. Deter- 
mine the number of cubic centimeters of acid neutralized by the 
ammonia and multiply this by the nitrogen factor of the acid. In case 
the acid is Fifth Normal this factor will be .0028. Divide the grams of 
nitrogen by the weight of the sample and multiply by 100 and the 
result will be percentage of nitrogen. 

(e) Total Potassium. This test is carried out as given on page 147, 
Bulletin 105, Bureau of Chemistry, Department of Agriculture. One 
gram of soil, very finely pulverized, 1 gram of ammonium chloride, 
and 8 grams of calcium carbonate thoroughly ground in an agate 
mortar are fused as directed in Fresenius' " Quantitative Analysis," 
Vol. 2, page 1175, and by Hillebrand in Bulletin 305 of the United 
States Geological Survey, where an illustration of the apparatus is 
given. The fused mass is transferred to a porcelain dish, slaked with 
hot water, finely ground with an agate pestle and transferred to a filter. 
After washing with about 600 cubic centimeters of hot water, the fil- 
trate and washings are run to dryness in a Jena beaker, taken up with 



156 



CHEMISTRY OF FARM PRACTICE 



hot water and again filtered, acidified with hydrochloric acid, con- 
centrated to about 10 cubic centimeters, and U cubic centimeters of 




0> 



Oh ^ 

w C 

.2 

II 

oB 

2 ^ 

c 



a; 
,4 



a platinum chloride solution (10 cubic centimeters containing 1 gram 
platinum) added. This is then evaporated to a sirupy consistency, 



MEASURING PLANT FOOD REQUIREMENTS 157 

taken up and washed about fifteen times with 80 per cent alcohol, 
three times with ammonium chloride solution, and again fifteen times 
with alcohol. The precipitate is then washed through the filter with 
hot water into a platinum dish, evaporated on the steam bath to dry- 
ness and heated in an air oven at 110° C. for an hour, cooled in a 
desiccator, and weighed as K 2 PtCl 6 . Duplicate samples should 
not differ more than 1.5 milligrams in the final weight. The weight 
of K 2 can be determined by multiplying the weight of the K 2 PtCl 6 
by the factor .1941. 

A correction must be made for the amount of potassium in the 
reagents, which is found by making a blank determination, using no 
soil. 

(Ammonium chloride solution is made by dissolving 200 grams 
NH 4 C1 in 1000 cubic centimeters water and saturating with K 2 PtCl G .) 
(/) Calcium. Calcium may be determined as described by Hop- 
kins in his Soil Fertility and Permanent Agriculture, page 632. Five 
grams of soil (or less if high in calcium) are decomposed by heating 
10 grams of sodium peroxide in an iron crucible. This is then taken 
up with water and hydrochloric acid and made up to 500 cubic centi- 
meters, as in the phosphorus determination. After being allowed to 
settle over night, 200 cubic centimeters of the supernatant solution 
are heated to boiling and precipitated from the hot solution with 
ammonia. The precipitate is filtered out on a 15-centimeter filter 
and washed with hot water until but a slight test for chlorides is 
given with silver nitrate. The filtrate is again evaporated to dryness 
and heated (to dehydrate any remaining silica), taken up with water 
and hydrochloric acid, brought to a boil, and ammonia added to pre- 
cipitate any remaining aluminum. The precipitate is filtered out on 
a small filter and washed with hot water. It should not be washed 
more than necessary to remove the chlorides, as the wash water car- 
ries aluminum through into the filtrate. On heating this filtrate and 
allowing it to stand overnight, more aluminum may be found to pre- 
cipitate out. All of the aluminum must be removed by repeated pre- 
cipitations. The solution is then made slightly alkaline with ammonia, 
brought to a boil, and to it is added slowly, while it is being stirred, 
enough concentrated ammonium oxalate solution to precipitate the 
calcium and to change the magnesium to the oxalate. After boiling 
until the precipitate has a granular appearance, it is allowed to stand 
three hours or longer, decanted into a filter, and washed twice by decan- 
tation. The precipitate in the beaker is then dissolved with a few 
drops of hydrochloric acid, a little water added, and the calcium 
reprecipitated, boiling hot, by adding ammonium hydroxide to slight 
alkalinity. A little ammonium oxalate is added, the solution allowed 



158 CHEMISTRY OF FARM PRACTICE 

to stand as before, and filtered through the same filter, washed free 
from chlorides with hot water, the filter burned and the precipitate 
ignited in a blast until it ceases to lose weight, and weighed as calcium 
oxide (CaO). This weight multiplied by the factor of calcium in 
calcium oxide (7129) will give the weight of calcium from which the 
percentage may be obtained by dividing by weight of the sample 
taken for analysis. 

111. Field Tests. The best measure of the amount of 
available plant food in a soil, and of food deficiencies, is 
obtained by actual field tests extending over a number of 
years to eliminate varying seasonal conditions and using 
as many crops as possible to test out crop peculiarities. On 
account of the expensive nature of such experiments they 
must usually be left to the State Experiment Stations, and 
those interested in soil chemistry will do well to study what 
has been done by various States as published in State 
Bulletins. It would be of great value if test farms could be 
maintained on every large and distinct soil type. The crops 
that, are generally grown on this distinct type should be 
tested in order that the information might be definite, and 
this information should be available to the farmers living 
within the area tested in order that they might apply the 
knowledge thus gained in their own farming. 

The simplest effective form of field test consists in a 
number of plots on which may be tested the value of 
each single element to a given crop; then of every possible 
combination of two elements; and, finally of all elements. 
It is best to provide as many duplicate plots as there are 
years in the rotation employed, and, in tins way to pro- 
duce every crop, every year, thus eliminating varying seasonal 
conditions. These elementary tests may be enlarged to 
include a comparison of the different sources of each ele- 
ment of plant food, varying relative proportions of the three 
most important elements, nitrogen, potassium and phos- 
phorus, and different cultural methods used in connection 
with fertilizing. A combination of two sources of nitrogen 
is often most effective. 



MEASURING PLANT FOOD REQUIREMENTS 159 




\(\() 



CHEMISTRY OF FARM PRACTICE 



Table XIV shows an effective three-year test, using the 
common three-year rotation so much advised for Southern 
conditions. 



TABLE NO. XIV.— AN ELEMENTARY FERTILIZER TEST IN 
CONNECTION WITH A THREE-YEAR ROTATION 

Corn and COWPEAS, Followed by Oats OR Oats and Vetch, 
Followed uy Cowpeas, Followed by a Cover Crop, PREF- 
ERABLY A LEGUME FOLLOWED BY COTTON, FOLLOWED BY A 

Cover. 















TJ 


b 
























cu 


^2 


^6 


n B 


2 '55 

5JS 






S 
p 

'53 

CO 

03 




efl O 


03 3 


3 3 


c 

4) 

M 
O 


o 

XI 

g, 




at 

ll 

ten 


a to 

S 2 


5*8 

m O 


~-B o 

Ml 


♦j 


o 


o 


5 Oh 




i&H tf 


y 


Ph 


Ph 


2 


y 


y 


Ph 


Z 



















Oats or Oats and VETCH FOLLOWED uy COWPEAS, FOLLOWED BY a 

Coveh Crop, Preferably a Legume, Followed by Cotton, 
Followed m a Cover Chop, Followed by Corn and Cow- 
peas. 















T3 


e 

3 








u 


^2 


T3 d 

c £ 


^P 


S'S 

o2 






a 




03 O 


03 3 


3 3 
















a 

CD 
M 

o 


o 


9 
1 






a- 2 

£ o 


8 1? 

0>4f 

■ 




§ 


o 




o 


.■§Ph 


Jjpn 


c Ph 


~Ph C9 


y 


Ph 


CM 


y 


X 


Z 


Pm 


z 



MEASURING PLANT FOOD REQUIREMENTS 161 

TABLE NO. XIV.— Continued. 

Cotton Followed by a Cover Chop, Followed by Corn and 
Cowpeas, Followed by Oats or Oats ind Vetch, Followed 
bi Cowpeas, Followed by a Cover Choi-. 















-O 


s 








e 


a u 


a S 


c 

2 s 


si 




3 


£ 

3 

.-3 




gj 


c9 - 


3 3 


o 2 


c 
i 

C 




a 


£ 


5$ 


c 3 

MS 

£ o 


5 3 
73 




£ 


J 







~=H 


S&< 


§* 


§Ph § 


A. 


5 


&H 


fe 


A, 


A 


&H 


A, 



The plan as outlined serves to show a simple fertilizer 
tost in connection with a three-year rotation; it may be 
enlarged or modified to cover any desired scope or condi- 
tion, or it may be used simply to test a single crop. In 
making fertilizer tests, the most approved agricultural 
methods for maintaining fertility should be followed, unless 
the object of the experiment is to determine the plant food 
requirements under a one-crop system. 

The individual farmer should avail himself of all the data 
issued by his own and neigh boring Experiment Stations, 
and it will often prove profitable for him to conduct simple 
tests himself. He should be familiar with the plant food 
content o( his various soil types, procured by soil analyses, 
for this shows the amount of potential plant food in his 
soil, and he has at his command the various agencies already 
discussed for bringing this food into availability. 



CHAPTER XVI 
MIXING OF FERTILIZERS 

112. Advantages of Home-Mixing. Phosphorus, ni- 
trogen and potassium are the three elements most usually 
found necessary to be supplied to a soil to keep up its 
fertility. The sources of these elements have been dis- 
cussed. The next consideration is how to apply most eco- 
nomically these purchased plant foods. 

Fertilizer factories are equipped with machinery that will 
mix thoroughly the raw materials, provided their work is well 
done. That this work is not always thoroughly done and 
that the materials are not always compounded so as to ap- 
proximate the desired mixture, is readily seen by examining 
any of the many Fertilizer Control Reports issued from the 
various Experimental Stations. When fertilizing materials 
are mixed, it is extremely difficult to determine with any 
degree of exactness the kind and proportion of all of the 
raw materials used. Due to this fact, a small amount of 
cheap and unavailable plant food, especially low-priced 
nitrogen, can be, and often is, worked into the mixture. The 
fertilizer manufacturers charge for mixing from S3 to $7 per 
ton. There are a number of formulas that farmers have 
become accustomed to buy of which some are very low grade. 
In mixing such formulas, the manufacturer must necessarily 
add some " make- weight " to his high-grade materials to 
bring the mixture to the desired percentage. This " make- 
weight " is known as the filler. 

The transportation and hauling of filler is a heavy and 
unnecessary expense that can be avoided by the purchase 
and home-mixing of high-grade materials. The greatest 
advantage to be gained by the home-mixing of commercial 

162 



MIXING OF FERTILIZERS 



163 



fertilizers lies in the fact that the sources from which the 
phosphorus, nitrogen, and potash are derived are then known. 
A thorough knowledge of the relative availabilities of the 
different sources of commercial fertilizers, and of their 
actions under different crops, will enable the farmer to select 
wisely materials the fertilizing values of which are known. 

113. Fertilizers may be Thoroughly Mixed on the Farm. 
The mixing of fertilizers can be thoroughly done on any 
farm, as has been shown by the South Carolina Experi- 
ment Station. When practicable, an out-building with a 



I 




A B 

Fig. 63. — Diagram showing relative composition and value of fertilizers: 
A, low grade; B, medium grade; C, high grade. (Farmers' 
Bulletin 457, U. S. Dept. Agr.) 

tight floor is preferable for the mixing, because the work 
can be done when weather conditions would prevent out- 
side work. If no tight floor is available, one may be made, 
preferably under a shed, by taking straight-edged boards 
about 1 inch in thickness, laying them on a level place 
and keying them up tight. A floor 8 feet wide and 12 feet 
long, surrounded on three sides by upright boards 12 inches 
wide, will suffice for the mixing. 

The raw materials are generally purchased in sacks. If 
a sufficient quantity is mixed to warrant the purchase in 
car-load bulk shipments, it will usually be advisable to buy 



164 



CHEMISTRY OF FARM PRACTICE 



a machine for mixing. The formula having been worked 
out, and knowing that 1000 pounds makes a good quantity for 
two men to manipulate, one-half of the materials necessary 
to make a ton of fertilizer is poured in the middle of the 
floor in alternate layers, beginning preferably with the acid 
phosphate. Two men can perform the mixing most ad- 
vantageously, one mixing with a hoe, and the other with a 
spade or shovel. In the case of the mixture made at the 
Station referred to, the mass was hoed and shoveled first 
to one corner, then to the other corner, and once diagonally 
across the 8 by 12 floor. Samples were taken of the un- 
mixed materials and of the mixed materials. Table XV 
may be taken as a typical analysis of the result of such 
mixing. 



TABLE XV.— AN EXAMPLE OF THE THOROUGHNESS 
OF HOME-MIXING OF FERTILIZERS 





Lbs. of To- 
tal Phos- 
phoric Acid 
(P2O6). 


Lbs. of Ni- 
trogen (N) 
Equivalent 
to Ammonia 
(NHs). 


Lbs. of Wa- 
ter-soluble 
Potash 
(K 2 0) 


800 lbs. 17.28% (P 2 5 ) acid phos- 
phate contains 

400 lbs. 8.14% (NH 8 ) 2.91% 
(P 2 5 ) 1.70% (K 2 0) cottonseed 
meal contains 


138.2 
11.6 


32.6 


6.8 


65 lbs. 48.06% (K 2 ) muriate of 
potash contains 


31.2 


1265 lbs 


149.8 
11.84 
11.77 


32.6 
2.58 
2.76 


38.0 


Mixture contained theoretically. . 
Mixture analyzed 


3.00 
3.01 







In making a home-mixture, it is very desirable to use 
some material that acts as a good dryer. Cottonseed meal 
is a most excellent dryer. Rape meal, linseed meal, and 
muck are also good dryers. 

In the mixture mentioned, it was found that two men 



MIXING OF FERTILIZERS 165 

can mix from 6 to 8 tons per day, weighing out the materials 
when fractions of a sack are used and assuming the weight 
on the sack as accurate when full sacks were used. In the 
formula noted, only the muriate of potash was weighed. 
The mixed material was replaced in the sacks from which 
the raw materials were removed. The cost of mixing each 
ton can be computed by dividing the wages of the men by 
the number of tons mixed. It will usually amount to less 
than 50 cents per ton. 

114. Educational Influence. An advantage of the home- 
mixing of fertilizers, not often considered, is that it necessi- 
tates a more thorough knowledge of fertilizing materials and 
it is a strong incentive to study, for fertilizing materials 
cannot be indiscriminately mixed. However, the incom- 
patibilities are few and easily explained. The chart, Fig. 
64, shows the materials that may be mixed advantageously, 
and the materials that should not be mixed. This chart, 
which had its beginning in a German publication, has been 
modified from time to time as data have been secured. It 
is modified from the chart given in Bulletin 388 of the Office 
of Experiment Stations, because it has been shown at the 
South Carolina Experiment Station that the potash content 
both of muriate of potash and kainit is rendered partly 
insoluble by mixing with basic slag or Thomas phosphate; 
and the chart has been made to conform to this fact. 

115. The Calculation of Formulas. Six forms of cal- 
culations are commonly met with in connection with the 
home-mixing of fertilizers. 

1. Given the percentage and weights of materials; 
calculate the formula. 

2. Given the materials and their analyses and the com- 
position of the formula desired ; calculate the weight of each 
material required. 

3. Given the materials too low in composition for 
making a formula of high percentage composition; over- 
come the difficulty. 



166 



CHEMISTRY OF FARM PRACTICE 



4. Given the high-grade materials; reduce to the pro- 
portion of a low-grade formula and avoid the use of a 
filler. 

5. To determine the amount and composition of a 
fertilizer when a portion is used under the crop and the 
remainder as a side application or topdressing. 

6. To convert a fertilizer from one formula to another. 
Examples of each form of calculation are given as 

types of the work involved. 

In the fertilizer trade, the term unit is often used. A 
unit is 1 per cent of a ton, or 20 pounds. In making these 
calculations, it must be remembered that per cent means 
pounds in a hundred pounds of material. 

(1) The percentage and weight of material being given, 
calculate the formula. 

Problem: Given, 1000 pounds of 16 per cent avail- 
able acid phosphate (P2O5), 100 pounds of muriate of potash, 
48 per cent water-soluble potash (K2O) and 900 pounds of 
cottonseed meal that will analyze nitrogen equivalent to 
7 per cent ammonia (NHs),2per cent phosphoric acid (P2O5) 
and 1.5 per cent of water-soluble potash (K2O). 

A good way to outline this calculation is as follows: 



3 


Percentage, Composition, and Source of 
Material. 


Lbs. of 
Nitrogen 
(N) equiv- 
alent to 
Ammonia 
(NHs). 


Lbs. of 
Phos- 
phoric 
Acid 
(P2O5). 


Lbs. of 
Water- 
Soluble 
Potash 

(K2O). 


1000 


16% P2O5 acid phosphate will fur- 
nish 


63.0 


160.0 
18.0 




900 
100 


7% NHa— 2%P 2 6 — 1.5% KaO C.S. 

meal will furnish 

48% K2O muriate of potash will 

furnish 


13.5 
48.0 










2000 


Formula 


63.0 


178.0 


61.5 




3.15% 


8.9% 


3.08% 









MIXING OF FERTILIZERS 



167 



The formula is obtained by dividing the content in pounds 
of each constituent by twenty, the number of hundred 
pounds in the mixture, and the result is the number of pounds 
of the constituent in 100 pounds of material, or the per- 
centage composition. 

(2) Given, the materials and their analyses and the com- 
position of the formula desired; calculate the weight of each 
material required./' 



Superphosphate 



Thomas slag 




Lime nitrogen 
(calcium cyanamid)' 



Barnyard manure 
guano 



Norwegian nitrate 
(basic calcium 
nitrate) 



Nitrate of soda 



Fig. 64. — Diagram indicating what fertilizer mat rials may and may 
not be safely mixed. The dark lines unite materials which should 
never be mixed, the double lines those which should be applied 
immediately after mixing, and the single lines those which may be 
mixed at any time. 



Problem: Make a fertilizer analyzing nitrogen equiva- 
lent to 4 per cent of ammonia, 8 per cent phosphoric acid, 
and 4 per cent water-soluble potash. Use 150 pounds of 
nitrate of soda as a source for a part of the nitrogen and 
derive the balance of the nitrogen from that contained in 
ground fish scrap. The ground fish scrap contains nitro- 
gen equivalent to 10 per cent of ammonia, and, in addition, 
6 per cent of phosphoric acid. The potash is to be derived 



168 CHEMISTRY OF FARM PRACTICE 

from muriate of potash. The phosphoric acid is to be 
derived from 16 per cent acid phosphate. 

This calculation should be handled as follows: The 
number of pounds of plant food required for a ton of this 
material is nitrogen equivalent to 80 pounds of ammonia, 
160 pounds of actual phosphoric anhydride (P2O5), and 
80 pounds of water-soluble potash. There is a specified 
amount of one material to be used as a source of nitrogen, 
150 pounds of nitrate of soda which will contain nitrogen 
equivalent to 18 per cent of ammonia or 27 pounds in the 
150 pounds of material. Nitrogen equivalent to 80 pounds 
of ammonia is required; so 27 pounds furnished by the 
nitrate of soda must be deducted, leaving 53 pounds to be 
furnished by ground fish scrap which contains nitrogen 
equivalent to 10 per cent of ammonia ; hence it will require 
530 pounds of ground fish scrap to furnish the remainder 
of the nitrogen. In addition to the nitrogen content of 
the fish scrap, this material carries 6 per cent of phosphoric 
acid, which is equivalent to 31.8 pounds of phosphoric acid. 
The amount of phosphoric acid required is 160 pounds, less 
32 pounds derived from the ground fish scrap, leaving 128 
pounds of actual phosphoric anhydride to be furnished by 
16 per cent acid phosphate. The number of hundred 
pounds of acid phosphate required can be determined by 
dividing the number of pounds required, 128, by the num- 
ber of pounds of phosphoric anhydride contained in 100 
pounds of acid phosphate, 16, in this case. The number 
of hundred pounds of muriate of potash to use is determined 
by dividing 80, the number of pounds of actual potash, by 
48, the number of pounds of potash contained in 100 pounds; 
80 -i- 48 = 1.666, or 167 pounds. This form of calculation is 
the one most used by fertilizer manipulators in calculating 
their formulas, 



MIXING OF FERTILIZERS 
Tabulating, we have the following: 



169 



•a 

is 



Source and Composition of Material. 



Lbs. of 
Nitrogen 
(N) equi- 
valent to 
Ammonia 

(NHs). 



Lbs. of 
Phos- 
phoric 
Acid 
(P2O5). 



Lbs. of 
Water- 
Soluble 
Potash 
(K2O). 



150 
530 

800 
157 
353 

2000 



18% (NH 3 ) nitrate of soda 

10% (NH 3 ) and 6% (P 2 5 ) ground 

fish 

16% (P2O5) acid phosphate 

48% (K2O) muriate of potash 

Make-weight filler 



27.0 
53.0 



32.0 

128.0 



80.0 



160.0 



Formula. 



4.0% 



0% 



so 



80 



4.0% 



(3) Given, material too low in composition to make a 
formula of high percentage composition; overcome the difficulty. 

Problem : To apply 1000 pounds of a fertilizer per acre 
for truck, analyzing nitrogen equivalent to 5 per cent 
ammonia, 8 per cent phosphoric anhydride, and 8 per cent 
potash. Source of phosphoric acid, 14 per cent acid phos- 
phate ; source of nitrogen, ground fish scrap containing nitro- 
gen equivalent to 10 per cent ammonia and 6 per cent avail- 
able phosphoric acid; source of potash, sulphate of potash 
containing 48 per cent water-soluble potassium oxide (K2O). 

Apply the same process outlined in (2), whereby it is 
found that 1000 pounds of dried ground fish, 714 pounds 
of 14 per cent acid, and 333 pounds of sulphate of potash 
contain the plant food desired for compounding 1 ton of 
fertilizer analyzing nitrogen equivalent to 5 per cent of 
ammonia, 8 per cent phosphoric anhydride, and 8 per cent 
water-soluble potash; but that the mixture weighs 2047 
pounds instead of 2000 pounds. Therefore the plant food 
is mixed in the same proportions as a " 5-8-8 " fertilizer 
(fertilizer containing 5 per cent ammonia, 8 per cent phos- 



170 



CHEMISTRY OF FARM PRACTICE 



phoric anhydride and 8 per cent water-soluble potash); 
but due to the increased weight, the per cent is corre- 
spondingly diminished. 

The results are tabulated as follows: 





Percentage, Composition and Source of 
Material 


Lbs. of 
Nitrogen 
(N) equi- 
valent to 
Ammonia 

(NH 3 ). 


Lbs. of 
Phos- 
phoric 
Acid 
(P 2 6 ). 


Lbs. of 
Water- 
Soluble 
Potash 

(K 2 0). 


714 
1000 

333 


14% (P 2 6 ) acid phosphate 

10% (NH 3 ) ammonia and 6% phos- 
phoric anhydride dried ground fish 
48% (K 2 0) sulphate of potash 


100.0 


100.0 
60.0 


160.0 


2047 


20.47 


100.0 


160.0 


160.0 




Formula 


4.89 


7.82 


7.82 









Therefore the number of pounds to be applied that will 
contain the same amount of plant food as 1000 pounds of a 
5-8-8 fertilizer can be calculated by making use of the follow- 
ing proportion: 

2000 : 2047 = 1000 : z = 1024 pounds. 

(4) Given, high-grade materials; make to the proportion 
of a low-grade formula, and avoid the use of a filler. 

Problem: Calculate a formula analyzing nitrogen 
equivalent to 3 per cent of ammonia, 8 per cent of available 
phosphoric acid, and 3 per cent of water-soluble potash, 
one-third of the nitrogen to be derived from sulphate of 
ammonia, which contains 24 per cent of ammonia, and 
two-thirds from cottonseed meal; the phosphoric anhydride, 
from 16 per cent acid phosphate; and the potash, from 48 
per cent muriate of potash. Calculate the analysis of the 
formula if no filler is added, and the number of pounds of 
this mixture equivalent to 500 pounds of a " 3-8-3 " fer- 
tilizer. 



MIXING OF FERTILIZERS 171 

(a) Proceed as in (3). In this case there is a difference 
from the type given under (3) in that there are two sources 
of nitrogen given, but the amount to calculate to each source 
is also fixed, hence we find 571 pounds cottonseed meal, 
7-2-1.5, will carry nitrogen equivalent to 7 per cent of 
ammonia and that 83 pounds of sulphate of ammonia 
will carry one unit of ammonia. The available phosphoric 
anhydride not furnished by the content of the 571 pounds 
of cottonseed meal will be furnished by 932 pounds of 
16 per cent acid phosphate; and the water-soluble potash 
not furnished by the water-soluble potash content of 1.5 
per cent contained in the cottonseed meal will be furnished 
by 107 pounds of 48 per cent muriate of potash. 

(6) Proceed as in (1). Adding we find that 1693 pounds 
of a mixture of cottonseed meal, sulphate of ammonia, acid 
phosphate, and muriate of potash in the proportions shown 
under (a) contains nitrogen equivalent to 60 pounds of 
ammonia, 160 pounds of phosphoric anhydride, and 60 
pounds of water-soluble potash; hence, if we divide these 
figures by 16.93, we will obtain the number of pounds of 
actual plant food in each hundred pounds of the mixture 
or the per cent., 9.6 per cent available phosphoric acid, 
nitrogen equivalent to 3.6 per cent ammonia, and 3.6 per 
cent of water-soluble potash. 

(c) The number of pounds of this mixture equivalent 
to 500 pounds of a 3-8-3 fertilizer is solved as under (3) : 

2000 : 1693 = 500 : a; =423 pounds. 

This proportion is based on the fact that 2000 pounds, 
the weight of a ton, is to 1693 pounds, the weight of the 
mixture containing the amount of plant food in the ton, as 
500 pounds, the portion of the ton used, is to x, x repre- 
senting the proportion of the mixture equivalent to 500 
pounds of 3-8-3 fertilizer. To use this mixture on the 3-8-3 
basis 423 pounds should be applied where 500 is called for. 

(5) To determine the amount and composition of a fer- 



172 CHEMISTRY OF FARM PRACTICE 

tilizer when a portion is used under the crop and the remainder 
as a side application or topdressing. 

Problem: Suppose that 500 pounds of a 3-8-3 mix- 
ture is applied to corn land before the crop is planted, 200 
pounds of 7-5-5 mixture is applied at the time of the second 
cultivation of the crop, and that 100 pounds of nitrate of 
soda is applied when the plants are about 4 feet tall, what 
percentages and what composition will the entire fertilization 
give? 

This is a different application of the principles given 
under (1); however, the same type will serve as an illus- 
tration. The calculation shows that the entire application is 
800 pounds of fertilizer analyzing nitrogen equivalent to 
5.88 per cent of ammonia, 6.25 per cent phosphoric acid, 
and 3.13 per cent of water-soluble potash. 

(6) To convert fertilizers from one formula to another. 

Problem : Convert a 4-8-4 fertilizer to a 3-9-2 formula, 
using dried ground fish, 10 per cent ammonia and 6 per 
cent available phosphoric acid, and 16 per cent acid phos- 
phate. Calculate the number of pounds of each of these 
materials and of filler. An inspection of the two formulas 
shows that the greatest difference is in the potash content 
of the two formulas, hence the potash content of the 4-8-4 
fertilizer will limit the number of pounds that can be used. 
A ton of 4-8-4 fertilizer contains 80 pounds of potash, while 
a ton of 3-9-2 fertilizer contains only 40 pounds of potash, 
therefore 1000 pounds of the 4-8-4 fertilizer can be used. 
This leaves 20 pounds of nitrogen and 100 pounds of phos- 
phoric acid to be furnished by dried ground fish and acid 
phosphate. The nitrogen is the smallest amount and should 
be supplied first because the dried ground fish also furnishes 
some phosphorus, which must be deducted from the balance 
to be furnished before the amount of acid phosphate is cal- 
culated. Twenty pounds of nitrogen is furnished by 200 
pounds of dried ground fish analyzing nitrogen equivalent 
to 10 per cent of ammonia, 6 per cent or 12 pounds of phos- 



MIXING OF FERTILIZERS 



173 



phoric acid is also furnished, and this amount, deducted from 
100 pounds, leaves 88 pounds to be furnished by 16 per 
cent acid phosphate. Sixteen will go into 88 five and one- 
half times, hence 550 pounds of acid phosphate will be re- 
quired. Adding, we have 1750 pounds of material to which 
must be added 250 pounds of make-weight or filler. 

Type of conversion of fertilizer from one formula to 
another: 



"3 


Source and Composition of Material. 


Nitrogen 
equiv- 
alent to 
Lbs. of 
Ammonia 


Lbs. of 
Phos- 
phoric 
Anhy- 
dride. 


Lbs. of 
Water- 
soluble 
Potash 
(K2O). 


1000 


4-8-4 fertilizer 


40.0 
20.0 


80.0 

12.0 
88.0 


40 


200 


Dried ground fish 10% NH 3 — 6% 
P,0 5 ' 




550 


16% acid phosphate. 




?50 


Filler 












2000 




60.0 


180.00 


40.0 




3.0% 


9.0% 


2.0% 



In the above calculations the plant food elements have 
been computed on the basis of the phosphorus combined 
as phosphoric anhydride (P2O.5), the nitrogen as ammonia 
(NH3), and the potassium as potassium oxide (K2O). The 
reason for this is that it is on this basis that it has become 
customary to buy and sell the elements. 

The above types will cover all of the contingencies likely 
to arise in the home-mixing of fertilizers. 



CHAPTER XVII 
ANIMAL NUTRITION 

116. Purposes of Animal Food. Food serves the animal 
in three ways. 

1. To act as a fuel to keep up the temperature above 
that of the surrounding air. This is accomplished by the 
oxidation of the combustible portion of the food through- 
out the body in the capillaries wherein the oxygen in the 
blood corpuscles comes in contact with combustible matter 
in the blood serum. 

2. To furnish energy by which the mechanical or mental 
work of the body may be produced. 

3. To build up or keep in repair the bodily structures. 

117. Classes of Foods. Plants can sustain themselves 
upon very simple foods such as water, carbon dioxide and 
mineral salts, while animals are so constructed that they de- 
mand more highly organized foods and are therefore depen- 
dent upon plant structures or upon animals that subsist 
upon vegetable food. 

Foods of animals fall into one of four classes: 

1. Proteins. These are composed of carbon, hydrogen 
and oxygen with a rather large amount of nitrogen (16 per 
cent) and generally small portions of sulphur and iron. The 
amount of protein is calculated by multiplying the nitrogen 
content of the material by the factor 6.25. Proteins are 
utilized by animals to build up worn-out muscular tissue. 
They are found in the gluten of flour, beans, nuts and 
generally in the seeds of plants, in lean meat, milk, cheese 
and whites of eggs, as well as in various feeds. 

2. Carbohydrates. These are made up of carbon, hydro- 
gen and oxygen, the two latter in the same proportion as 

174 



ANIMAL NUTRITION 175 

they are found in water. They supply the animal with heat 
and energy. Starches and sugars are carbohydrates. Car- 
bohydrates are also contained in potatoes, in wheat flour, 
oatmeal and other cereals. 

3. Fats. These are composed almost entirely of carbon, 
hydrogen and oxygen with a high percentage of carbon. 
Like the carbohydrates they supply heat and bodily energy, 
having per pound more than twice the value of the carbo- 
hydrates. Fats are found in butter, meat fats and the oils 
of various nuts. The fats stored up in the body are mainly 
derived from the carbohydrate food. 

4. Mineral Compounds. These have varied composition, 
but very few contain carbon. They serve a variety of pur- 
poses in the body. Water and the salts of sodium and cal- 
cium are the most important articles of this class of foods. 

118. Development of a Science of Animal Nutrition. 
The science of animal nutrition had its beginning in 1859, 
when Grouven suggested the first feeding standard for farm 
animals. Grouven's standard was based upon the total 
amount of crude protein, carbohydrates, and fat contained 
in the material fed. Later work has shown that this was 
an irrational basis, because of the variation in the digesti- 
bility of these proximate constituents in different animal 
feeds. It is even more necessary to consider the digesti- 
bility of the feed for animals than it is to consider the avail- 
ability of a fertilizing material for plants, because, after a 
certain length of time, the feed undigested is voided by the 
animal, while the unavailable plant food remains in the soil 
and may later be made available by natural agencies. 

In 1864, Dr. Emil von Wolff presented a table of feed- 
ing standards based on the amount of digestible nutrients 
contained in each particular feeding stuff. Wolff's standard 
has sisce furnished the basis for rational feeding methods. 
In 1874, ten years after Wolff published his standard, 
Dr. Atwater brought it to the attention of the American 
people, and in 1880 Armsby published his " Manual of 



176 CHEMISTRY OF FARM PRACTICE 

Cattle Feeding." The Wolff standard was used unaltered 
until 1896, when as a result of further experiments, some 
alterations were made. It was presented annually from 
1896 to 1906 by Dr. C. Lehman, under the name of the 
Wolff-Lehmann Standards. Table XVI gives the last of 
these standards. 

119. Digestible Nutrients. The term digestible nutrient 
is applied to the digestible portion of feeds. The digestible 
nutrients are the carbohydrates, the fats and protein. 

The percentage of each feed that is digestible is deter- 
mined by feeding experiments with various classes of 
mature animals. Experiments show that ruminants digest 
the same kind of food about equally well, while horses and 
swine digest less fiber than do the ruminants; however, they 
seem to digest the concentrates about as well as the rumi- 
nants. Age and breed seem to have no definite influence on 
digestion. 

120. Metabolism. Metabolism is the process by which 
digested nutrients are used for the building of tissue and 
by which these tissues are broken down with the production 
of heat. The building-up processes are called anabolism, 
while the breaking-down processes are called catabolism. 

The digested sugars are taken up by the capillaries 
and carried into the veins, by which they are transferred to 
the liver, where they are made into glycogen or animal starch 
and stored temporarily as such. This constitutes the ani- 
mal's reserve supply of sugar, for it is reconverted into sugars 
and made use of by the animal as required, especially when 
work is being done. The fats seem to be absorbed as soaps 
and glycerin into the intestinal walls, where they are 
converted into neutral fats and find their way into the 
circulatory system. The products of the protein digestion 
are absorbed from the small intestines and converted into 
serum albumin and serum globulin, which are the nitrogenous 
materials used in the building of body tissues. All of these 
materials are transported by the blood to the various 



ANIMAL NUTRITION 



177 



TABLE XVI.— THE WOLFF-LEHMAN FEEDING 


STANDARD 




Per Day per 1000 


lbs. Live Weight. 




Dry 


Digestible Nutrients. 
















Mat- 


Crude 


Carbo- 




Sum of 


Nutri- 




ter. 


Pro- 
tein. 


hy- 
drates. 


Fat. 


Nut-i- 
e^ .. 


tive 

Ratio, 

1. 


1. Oxen: 


Lbs. 


Lbs. 


Lbs. 


Lbs. 


Lbs. 




At rest in stall 


18 


0.7 


8.0 


0.1 


7.5 


11.8 


At light work 


22 


1.4 


10.0 


0.3 


9.7 


7.7 


At medium work. . . 


25 


2.0 


ll.fi 


0.5 


12.0 


6.5 


At heavy work .... 


28 


2.8 


13.0 


0.8 


15.0 


5.3 


2. Fattening cattle: 














First period 


30 


2.5 


15.0 


0.5 


15.6 


6.5 


Second period 


30 


3.0 


14.5 


0.7 


17.0 


5.4 


Third period 


26 


2.7 


15.0 


0.7 


17.2 


6.2 


3. Milch cows: 














When yielding daily 














11.0 lbs. of milk... 


25 


1.6 


10.0 


0.3 


10.2 


6.7 


16.6 lbs. of milk.. . . 


27 


2.0 


11.0 


0.4 


12.2 


6.0 


22.0 lbs. of milk... . 


29 


2.5 


13.0 


0.5 


14.4 


5.7 


27.5 lbs. of milk... . 


32 


3.3 


13.0 


0.8 


16.0 


4.5 


4. Sheep: 














Coarse wool 


20 


1.2 


10.5 


0.2 


9.1 


9.1 


Fine wool 


23 


1.5 


12.0 


0.3 


10.5 


8.5 


5. Breeding ewes 




With lambs 


25 


2.9 


15.0 


0.5 


16.3 


5.6 


6. Fattening sheep: 














First period 


30 


3.0 


15.0 


0.5 


16.5 


5.4 


Second period 


28 


3.5 


14.5 


0.6 


16.9 


4.5 


7. Horses: 














Light work 


20 


1.5 


9.5 


0.4 


10.0 


7.0 


Medium work 


24 


2.0 


11.0 


0.6 


12.8 


6.2 


Heavy work 


26 


2.5 


13.3 


0.8 


15.5 


6.0 


8. Brood sows 


22 


2.5 


15.5 


0.4 


19.0 


6.6 


9. Fattening swine: 




First period 


36 


4.5 


25.0 


0.7 


31.2 


5.9 


Second period 


32 


4.0 


24.0 


0.5 


29.2 


6.3 


Third period 


25 


2.7 


18.0 


0.4 


22.0 


7.0 



178 



CHEMISTRY OF FARM PRACTICE 
TABLE XVI.— Continued 



10. Growing cattle: 
Dairy breeds. 



Age in 
Months 

2- 3 

3- 6 
6-12 

12-18 
18-24 



Av. Live Wt. 
per Head, Lbs 

150 

300 

500 

700 

900 



11. 



Growing cattle: 
Beef breeds. 



2- 3 

3- 6 
6-12 

12-18 
18-24 



160. 
330. 
550. 
750. 
950. 



12. Growing Sheep: 
Wool breeds. 



4- 6 

6- 8 

8-11 

11-15 

15-20 



60. 
75. 
80. 
90. 
100. 



13. 



Growing sheep: 
Mutton breeds. 



4- 6 

6- 8 

8-11 

11-15 

15-20 



60. 

80. 
100. 
120 
150 



Per Day per 1000 Lbs. Live Weight. 



Drv 
Mat- 
ter. 



Lbs. 

23 
24 
27 
26 
26 



23 
24 
25 
24 
24 



25 
25 
23 
22 
22 



26 
26 
24 
23 
22 



Crude 
Pro- 
tein. 



Lbs. 
4.0 

3.0 
2.0 
1.8 
1.5 



4.2 
3.5 
2.5 
2.0 
1.8 



3.4 
2.8 
2.1 
1.8 
1.5 



4.4 
3.5 
3.0 
2.2 
2.0 



Digestible Nutrients. 



Carbo- 
hy- 
drates. 



Lbs. 

13.0 
12.8 
12.5 
12.5 
12.0 



13.0 
12.8 
13.2 
12.5 
12.0 



15.4 
13.8 
11.5 
11.2 
10.8 



15.5 
15.0 
14.3 
12.6 
12.0 



Fat. 



Lbs. 
2.0 
1.0 
0.5 
0.4 
0.3 



2.0 
1.5 
0.7 
0.5 
0.4 



0.7 
0.6 
0.5 
0.4 
0.3 



0.9 
0.7 
0.5 
0.5 
0.4 



Sum of 
Nutri- 
ents. 



Lbs. 
21.0 
17.0 
13.7 
12.8 
11.8 



21.5 
19.0 
15.8 
13.9 
13.2 



18.4 
15.8 
12.8 
12.0 
11.0 



20.9 
17.8 
16.3 
13.8 

12.8 



Nutri- 
tive 
Ratio, 
1. 



4.5 
5.1 

6.8 
7.5 

8.5 



4.2 
4.7 
6.0 
6.8 
7.2 



5.0 
5.4 
6.0 
7.0 

7.7 



4.0 
4.8 
5.2 
6.3 
6.5 



ANIMAL NUTRITION 
TABLE XVI.— Continued 



179 





Per Day per 1000 Lbs. Live Weight. 




Dry 

Mat- 
ter. 


Digestible Nutrients. 




Crude 
Pro- 
tein. 


Carbo- 
hy- 
drates. 


Fat. 


Sum of 
Nutri- 
ents. 


Nutri- 
tive 
Ratio, 
1. 


14. Growing swine: 

Breeding stock. 

Age in Av. Live Wt. 
Months per Head, Lbs. 

2-3 50 

3-5 100 

5-6 120 

6-8 200 

8-12 250 

15. Growing, fattening 

swine: 

2-3 50 

3-5 100 

5-6 150 

6-8 200 

9-12 300 


Lbs. 
44 
35 
32 
28 
25 

44 
35 
33 
30 
26 


Lbs. 
7.6 

4.8 
3.7 
2.8 
2.1 

7.6 
5.0 
4.3 
3.6 
3.0 


Lbs. 
28.0 
22.5 
21.3 
18.7 
15.3 

28.0 
23.1 
22.3 
20.5 
18.3 


Lbs. 
1.0 
0.7 
0.4 
0.3 
0.2 

1.0 

0.8 
0.6 
0.4 
0.3 


Lbs. 

38.0 
29.0 
26.0 
22.2 
17.9 

38.0 
30.0 
28.0 
25.1 
22.0 


4.0 
5.0 
6.0 
7.0 
7.5 

4.0 
5.0 
5.5 
6.0 
6.4 



tissues nourishing the body and serve as a source of heat 
and energy. 

121. Rations for Various Purposes. A ration is the 
quantity of food consumed by animals per 1000 pounds of 
live weight during twenty-four hours. The age of the 
animal and the purpose for which it is kept exert important 
influences on the kind and amount of food that is desirable. 

122. Growth Rations. Young and growing animals 
need a ration that will produce bone and muscle. When 
maturity is reached, there is little subsequent increase in 
either the bones or the muscles. The bones, in part, and 
the ligaments, muscles, nervous system, and tendons con- 
sist almost entirely of protein, therefore the young and grow- 



180 CHEMISTRY OF FARM PRACTICE 

ing animals make economical use of large amounts of pro- 
tein. It is not desirable to feed large amounts of protein 
to mature animals unless they are either pregnant, or giving 
milk, or producing wool, because the protein eaten above the 
amount needed for maintaining the body tissues is un- 
economically used. 

The protein of the milk which the young animal takes is 
very largely stored in the body. Soxhlet found that 72.6 
per cent of the protein, 96.6 per cent of the lime, and 72.6 
per cent of the phosphorus fed in the milk was stored in the 
body of a calf between two and three weeks old. The 
proportion stored diminishes as the animal approaches 
maturity. 

Growing animals should get an abundance of succulent, 
highly nitrogenous forage plants. These plants usually 
contain a liberal amount of mineral elements. Some con- 
centrate (such as bran, meal, oats) is usually desirable and 
an abundant supply of common salt. 

123. Maintenance Rations. A certain amount of food 
is required by mature animals to perform the body functions, 
such as furnishing heat to maintain the body temperature, 
energy to perform the vital functions, and various materials 
to replace the waste tissue that is constantly being broken 
down. This is known as the* maintenance ration. If it is 
too much reduced, starvation will result. 

These rations may consist largely of coarse hay and straw 
or " roughages," as they are called. The main requirement 
is the production of heat, and roughages contain a large 
amount of carbonaceous material, which produces heat eco- 
nomically. Very little protein is required in the maintenance 
ration, because protein is only needed for the replacement of 
waste tissue, a requirement which is low in mature animals. 

Experiments have shown that the temperament of the 
animal, the condition with respect to flesh, the conditions 
under which the animal is kept, the body covering and the 
bodily surface exposed, and the severity of the weather all 



ANIMAL NUTRITION 181 

exert influence on the maintenance ration required. As 
wide a nutritive ratio as 11.8 parts of digestive carbohydrates 
to one part of digestive protein may be used successfully 
for a maintenance ration. The nutritive ratio is deter- 
mined by adding 2.25 times the digestible fat to the 
digestible carbohydrates, and dividing by the digestible 
protein. 

124. Fattening Rations. The main object of fattening 
is to improve the quality of the meat; the accumulation of 
fatty tissue is a secondary object. The formation of fat 
and its accumulation in the animal is governed by the quan- 
tity and quality of the food consumed above the amount 
required for growth and maintenance. It is difficult to 
fatten young animals on account of their tendency to make 
use of a large part of the food eaten for growth. Exertion 
or excitement of any kind lessens the amount of fat formed 
from a given quantity of feed. The fattening ration for 
beef animals depends upon their condition when feeding is 
begun. If the animals are thin, a ratio of one part of pro- 
tein to six parts of carbohydrate is recommended, allow- 
ing a liberal amount of protein during the first period of 
fattening, in order that the muscular tissues may be built 
up. From 12 to 15 pounds of digestible nutrients in the pro- 
portion already mentioned should be given per 1000 pounds 
of live-weight. For mature animals in good condition, 
a nutritive ratio as wide as 1 to 10 or 12 is suggested. The 
nutritive ratio will depend to some extent on the relative 
cost of feeds containing protein to the cost of carbohydrate 
feeds. In the Southern States, the cheap cottonseed meal 
will warrant a narrower ration, i.e., one having less carbo- 
hydrate in proportion to the protein than is usually recom- 
mended elsewhere. 

Hogs make good gains on a narrower nutritive ratio than 
is needed for steers. The ratios showing best results range 
from 1 to 6 in the beginning to 1 to 7 toward the end of the 
fattening period. It has been shown that 100 pounds of 



182 CHEMISTRY OF FARM PRACTICE 

dry feed consumed will form 6.2 pounds of increased weight 
in cattle, 8 pounds in sheep, and 17.6 pounds in hogs. An 
inspection of the quotations from the various stock markets 
will show that on this basis pork is the most profitable meat 
to produce. 

125. Milk-Cows' Ration. The WolfY-Lehmann standards 
advise for milk-cows a nutritive ratio of 1 to 5.7 (i.e., digesti- 
ble protein 1 part, digestible carbohydrates + (2.25 X fat) 
= 5.7 parts). For a cow that is expected to give 22 quarts 
of milk, 29 pounds of dry matter is recommended per 1000 
pounds of live-weight. The narrowest ration that is recom- 
mended in these standards is recommended for milk-cows. 
The feed of a dairy cow must of necessity contain a consider- 
able amount of concentrates which are high in price compared 
with roughages; but the value of the product will warrant 
the increased expenditure. In calculating a ration, it is 
not always practicable to get the exact ratio within the 
prescribed number of pounds of dry matter. If possible, 
the number of pounds of dry matter should be under rather 
than over the standard, because the digestive organs of a 
highly specialized animal should not be overtaxed. The 
dairy cow is essentially a machine for the transformation 
of feed into milk; hence every effort should be directed to a 
large production per animal so as to reduce the cost of main- 
tenance rations as low as possible by having fewer animals 
to maintain. With this end in view, the dairy cow, when in 
milk, should receive an abundant supply of concentrates 
even if she has a good pasture. While dry, she can be 
maintained like other animals, largely on roughage. 

126. Ration for Work Animals. The activity of the 
muscles during the performance of work greatly increases the 
amount of food required above a maintenance ration. It 
has been shown by repeated experiments that energy 
is derived most cheaply through the oxidation of carbohy- 
drates and fats in the body; that a sufficient supply of car- 
bohydrates and fats is an adequate source for all the energy 



ANIMAL NUTRITION 183 

needed; and that, if these are insufficient, the protein com- 
pounds may be drawn upon as a source of energy. This 
latter source makes the cost of the energy greater, and it 
also imposes extra work on the urinary system, through 
which the nitrogenous products of the oxidation of protein 
are removed. During work, the quantity of carbon dioxide 
exhaled is much increased, due to the greater quantity of 
carbonaceous matter that is oxidized. The latest investi- 
gations show that no more nitrogenous tissue is broken 
down by animals while at work than at rest. Working 
animals thus require a more concentrated feed and less 
roughage. 

The horse requires considerably less dry matter per 1000 
pounds of live-weight than do the ruminants, and its food 
should be rich and easily digested. Horses must be fed in 
accordance with the work that they are doing, the ration 
being reduced when at rest or light work, to secure economical 
results. It is advisable to give most of the roughage at 
night. A moderate but not an excessive amount of hay is 
desirable. The Wolff-Lehmann standards recommend a 
nutritive ratio of 1 to 6.2 for a horse on medium work, and 
Henry states that " from 10 to 18 pounds of concentrates 
should be fed, according to the severity of the labor, the 
total grain and hay averaging not less than 2 pounds per 
hundred pounds weight of the animal." 



CHAPTER XVIII 

FEEDS— THE CALCULATION OF RATIONS 

A brief discussion of some of the more commonly used 
feeds is given in the following paragraphs : 

1. The Concentrate Feeds — Cereals 

127. Corn. Corn is essentially a carbonaceous feed, 
and is not as good for growing animals as is oats. Corn has 
very marked heat-giving and fattening properties and, for 
this reason, it is quite extensively used for fattening steers, 
sheep and hogs. It is highly prized as a feed for work horses 
and mules, giving most satisfactory results. It is quite use- 
ful for making up a part of the carbohydrates in a balanced 
ration. 

128. Oats. Oats is an excellent feed for stock, because 
the nutrients are present in a good ratio for the work horse, 
the dairy cow, and for young and growing animals. Oats 
are used the world over as feed for horses, giving vigor and 
stamina. Ground oats have been found superior to wheat 
bran for producing both milk and butter-fat. The protein 
contained in oats shows a higher coefficient of digestibility 
than that of corn, while the carbohydrates of corn show a 
higher digestibility than those of oats. 

129. Barley. Barley is used for a stock feed mainly on 
the Pacific slope, where it flourishes better than corn or 
oats. In some cases, barley is injured for brewing purposes 
by bad weather at harvest time, while its value for feeding 
purposes is unimpaired. It is extensively used in foreign 
countries for pork production and for the feeding of dairy 
cows. It produces pork of excellent quality and, along 

184 



FEEDS— THE CALCULATION OF RATIONS 185 

with oats, is regarded highly as a feed for producing milk and 
butter fat. 

130. Dried Brewers' Grain. Dried brewers' grain is a 
by-product of barley, being the residue left from brewing. 
In brewing, the fermentable carbohydrates are converted 
into alcohol and the protein, fat, and crude fiber are largely 
left in the residue, hence dried brewers' grain is rich in 
these materials. The dry matter and carbohydrates of the 
dried brewers' grain are lower in digestibility than the same 
proximate constituents of barley, while, on the other hand, 
the protein and fat of the dried brewers' grain are more 
digestible than those of barley. 

131. Rye. Rye is not keenly relished by stock. It 
is subject, also, to a fungus disease, ergot, that may be 
injurious. 

132. Wheat. Wheat, on account of its cost of production 
and its value as a human food, cannot be used extensively 
for feeding stock. When fed to farm animals, it is best 
mixed with other grains, with the corn for work stock and 
with oats for growing stock. 

The by-products of the manufacture of wheat into flour — 
shorts, middlings and bran — are very valuable stock feeds. 

Wheat bran is the outer covering of the wheat kernel, 
and is that part which is first removed in the manufacture 
of flour. Its volume is large in proportion to its weight, 
therefore it is often used to give bulk to a feed ration. Bran 
contains a high percentage of crude protein and mineral 
matter. It is an excellent feed for breeding stock of all 
kinds, for horses, and for dairy cows. It serves to keep the 
animal's stomach in good order and to build up bone and 
muscles in young stock. It is also well suited for use in 
balancing the rations of dairy cows. 

Wheat middlings are composed of the part of the kernel 
below the bran. It is even higher in protein content than 
bran and is an excellent material to form a part of the ration 
of hogs and dairy cows. 



186 CHEMISTRY OF FARM PRACTICE 

133. Rice. Rice is used as a human food over a large 
part of the world. In the process of milling, there are 
several by-products which are of value as stock feed. The 
rough rice is put through a machine which removes the 
hull and leaves the rice grain intact. The grains are then 
rubbed by mechanical means until the skin and the flour 
at the eye of grain are removed. Some grains which are 
inferior are so abraded that they grind up. The material 
is then sifted to remove the flour, and the fine chaff is re- 
moved by fanning. This chaff is then mixed with the flour, 
forming what is known as rice flour or bran. 

Rice polish is obtained by the operation that rubs off 
the last covering layer and a good part of the starch. This 
is accomplished mechanically by rubbing the rice against 
pieces of moose hide or sheepskin. Rice polish contains a 
considerable amount of starch. 

Rice meal may prove injurious to the intestines of hogs, 
on account of the irritation caused by fine splinters of 
silicious material that find their way from the hulls into the 
meal. 

2. Highly Nitrogenous Concentrates 

134. Cottonseed Meal. Cottonseed meal, a by-product 
of the cottonseed oil mills, is the cheapest source of digestible 
protein that can be bought in the form of a concentrate. 
On this account, there is grave danger of too liberal use of 
it, especially in the Southern States. Where used in 
limited quantities, it is a most excellent source of protein. 
Enough cottonseed hulls to reduce the nitrogen to about the 
equivalent of 7 per cent of ammonia is often added, the 
crushers claiming that this promotes a more complete 
removal of the oil. The cottonseed cake used for domestic 
purposes is usually ground and placed in 100-pound sacks, 
which is a convenient weight for handling. Cottonseed 
meal is high in protein and fat, but low in digestible carbo- 
hydrates. 



FEEDS— THE CALCULATION OF RATIONS 187 

In the South many steers are fattened on cottonseed meal 
as the sole concentrate. They are started on a comparatively 
small amount, about 3 or 4 pounds per day, which is increased 
to as much as 8 or 10 pounds before the end of the feeding 
period. Cottonseed meal could be used to better advantage 
as a part of the ration, some concentrate carrying a larger 
percentage of carbohydrates being substituted as the other 
part. The excessive feeding of cottonseed meal over a long 
period of time has led to harmful effects; in some cases 
blindness and partial paralysis are induced, but no such 
results are obtained where it is properly mixed with other 
feeds. 

Cottonseed meal seems to vary in its poisonous qualities 
to hogs, some meals being quite toxic, while others have been 
fed in heavy amounts for a long period without producing 
death. Copperas has been used along with cottonseed meal, 
as an antidote, with good results. The feeder should real- 
ize that in feeding cottonseed meal he is using a cheap 
feed that may prove injurious, and the animals should be 
carefully watched. 

Cottonseed meal may be fed to work horses, brood mares, 
and colts in limited quantities of from 1 to 2 pounds daily. 
It gives the animals a good coat, and is keenly relished after 
they learn to eat it. For dairy cows the use of cottonseed 
meal to an amount not exceeding 5 pounds per 1000 pounds 
of live weight per day is to be recommended. Its excessive 
use has a tendency to raise the melting point of the 
butter. Cottonseed meal is giving good results as a poultry 
feed. 

135. Linseed Meal. Linseed meal is made by two proc- 
esses. The old-process meal is the residue obtained by 
expressing the oil while cold, by means of pressure. New- 
process meal is the residue of the extraction of the oil by 
means of naphtha, which is later driven off by steam. This 
cooking makes the crude protein slightly less digestible. 
The new process meal contains more crude protein, but only 



188 CHEMISTRY OF FARM PRACTICE 

about one-fourth as much crude fat, the new process being a 
much more effective means of removing the oil. 

Linseed meal may be fed in small quantities to all classes 
of live stock with excellent results. It is considerably 
higher in price than cottonseed meal, and, consequently, 
there is not the same tendency to over-feed it. 

136. Meat Scraps. Meat scraps, or tankage, is very 
high in protein. In buying tankage for feeding, care should 
be exercised to avoid buying acidulated tankage. Tankage 
is rather a high-priced source of nitrogenous feed. It has 
been used for cattle, sheep, hogs, and horses with good 
results. Parts from diseased animals are often incorporated 
in tankage, and infection from this source is possible, though 
improbable; not a case of such infection has been reported 
by any Station experimenting with this feed. In prep- 
aration, the tankage is cooked by means of steam under 
pressure to facilitate the removal of the grease. This 
treatment should produce a sterile condition. This form 
of protein does not seem to have its digestibility harmfully 
influenced because of the cooking, for the protein is given 
as 93 per cent digestible. Tankage is highly prized as a 
poultry feed. 

137. Dried Fish. Dried fish has been used to some 
extent as a feed for dairy cows without any harmful or 
objectionable influence on the quality of the milk. It is 
highly nitrogenous, containing as high as 48 per cent of pro- 
tein as well as a high percentage of fat, both of which are 
highly digestible. In the table of digestibility the protein 
is given as 93 per cent digestible and the fat as 98 per cent. 

138. Blood Meal. Blood meal is the richest available 
source of protein, and contains about 84 per cent, of which 
84 per cent is digestible. It has given good results when 
fed to hardworked horses at the rate of about 1 pound per 
day, and when fed to sickly calves in their milk at the rate 
of from a teaspoonful to a tablespoonful. When fed to 
pigs, 1 pound of blood meal may replace 12 pounds of skim 



FEEDS— THE CALCULATION OF RATIONS 189 

milk if mixed with some material that the pigs will eat, and, 
for lambs \ pound of blood meal may be fed per 100 pounds 
of live weight with good results. 

139. Soybean Meal. Soybean meal is highly nitrogen- 
ous, containing about 33.5 per cent of protein which shows 
a digestibility of 87 per cent. It forms a better feed after 
the oil is expressed than when the whole bean is ground and 
fed. 

140. Peanuts. Peanuts run high in both protein and fat, 
and form an excellent source of feed for hogs. Peanuts 
yield about 40 bushels per acre, and are best harvested by 
the hogs. Unless the fattening is completed by feeding 
corn, the lard will not solidify at ordinary temperatures. 
When the oil is extracted, the peanut meal may be used to 
some extent as a feed for stock. This meal contains the 
highest protein content of any vegetable material — about 
47 per cent. 

3. The Roughages 

141. Timothy. Timothy is the most popular hay for 
city markets, and serves well as a roughage along with such a 
concentrate as oats; but under farm conditions other hays 
are more cheaply grown, because they yield more heavily. 
The early cut timothy hay contains more protein in propor- 
tion to the carbohydrates present, and therefore is well 
suited to the requirements of dairy cows and young and 
growing stock. The late cut hay is better for horses and for 
fattening cattle. Late cutting also gives a better yield. On 
account of its quality, timothy is highly valued for horses, 
but it does not contain a large amount of digestible nutrients. 
Timothy is not an economical feed for fattening cattle nor 
for dairy cows; in fact, it is most valuable as a roughage for 
driving, saddle, and race horses. From the farmer's view- 
point, the chief value of timothy lies in the fact that it is an 
easily marketed hay. 

142. Cereals. The cereals are used to some extent as 



190 CHEMISTRY OF FARM PRACTICE 

roughages, and even where they are harvested and threshed, 
the straw has some value as roughage. 

Oat straw is the most nutritious of the straws, and may be 
used to advantage as a part of a maintenance ration. 

Oat hay is easily grown, and is much relished by stock. 
The time of cutting should be decided to some extent by the 
stock for which it is to be used. The protein content in- 
creases until early in the milk stage of growth, when the hay 
should be cut, if a maximum protein content is desired. Most 
of the starch in oats is formed after the beginning of the milk 
stage; hence, if a feed high in nitrogen-free extract is desired, 
the cutting should be delayed as long as possible, for there 
is a rapid increase in the total dry matter of about 40 per 
cent from the early milk stage to maturity, the combined 
starch and sugars increasing at this time from about 13 to 
30 per cent. For dairy cows and young and growing stock, 
the early cutting would be advisable. For feeding along 
with highly nitrogenous feeds, the later cutting will be best. 

143. Legumes. The legumes should be grown and used 
for roughage as much as possible on account of their beneficial 
influence on the soil, in addition to their high content of 
digestible nutrients. 

Alfalfa hay is especially valuable for practically all 
classes of stock. It is excellent for dairy cows and fattening 
steers. For dairy cows it may be used as a substitute for a 
small part of the concentrate, yielding cheaper milk; while 
in fattening beef cattle it may be used to a larger extent 
in replacing the concentrates. It has an especial value as 
a maintenance ration for young hogs, and can be used to 
some extent for fattening hogs. Sheep thrive on alfalfa 
hay. Work horses can use it to good advantage, but it is 
not advisable to feed it to driving horses. 

Red clover is much used in rotations in the Northern part 
of the United States. When well cured red clover hay is 
a desirable feed for horses. Experiments show that it gives 
splendid results for fattening beef cattle, both by reducing the 



FEEDS— THE CALCULATION OF RATIONS 191 

amount of concentrates necessary and by shortening the 
feeding period. For dairy cows, clover hay is a splendid 
roughage, being rich in protein and in mineral elements. It 
is excellent for young stock on account of its high content of 
bone- and muscle-producing materials. Clover is especially 
valuable as a feed for hogs. 

Crimson clover makes a hay of fair quality when cut early; 
if cut late, the blossoms are covered with very small barbed 
heads which may accumulate in spherical balls in the stom- 
achs of horses, and in some cases may stop up the intestines 
so that death may ensue. 

Japanese clover on rich land yields a hay of good quality. 

Canadian field peas or common field peas are grown in the 
Northern States along with oats for hay. This hay is both 
nutritious and keenly relished and fills very much the same 
place in the North as oats and vetch do in the South. 

Cowpea vines are harvested for hay in the Southern States. 
The vines should be cut about the time that the first pods 
begin to ripen, in order that a large yield may be secured 
and that the leaves may be cured along with the vines. It 
has been found that the leaves make up about 30 per cent of 
the weight of the hay and that they are much richer in pro- 
tein than are the stems. Cowpea hay can be successfully 
substituted for a part of the concentrate for dairy cows and 
for fattening steers. It can be used for a maintenance 
ration for mules on Southern farms during the winter 
months when they are not at work. 

Hairy vetch is adapted to a large part of the United 
States and makes a comparatively easily cured and nutri- 
tious hay. It should be sowed along with a cereal to support 
the vines. In the South these fields furnish good pasturage 
during the winter months when the land is dry enough 
for animals to walk on it. 

Soybeans are planted for a hay crop to some extent, and 
the cured vines yield a nutritious hay, which can be pro- 
duced at a low cost. Soybeans are more erect in their 



192 



CHEMISTRY OF FARM PRACTICE 



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23 -a 






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8 



$ | s s 

S S g 03 

co 5_ as 3 3 
« £T,o c fl 

k3 



2 S o 



e3 c3 c3 • 

asasoasasasas 
^^^3^3 o o " 



c3 

co o a g^: g 

fe Si 0) ^ r/j 5 

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Q 



194 CHEMISTRY OF FARM PRACTICE 

habit of growth than the running varieties of cowpeas; 
consequently, they are more easily cut and harvested. The 
Tennessee Station has obtained good results from feeding 
soybean hay to dairy cows; in fact, it proved superior to 
alfalfa hay. 

144. Composition and Digestibility of Feeds. Table 
XVII, which is compiled largely from Henry's " Feeds and 
Feeding," shows the composition and digestibility of a num- 
ber of feeding stuffs. 

145. The Calculation of Rations. The data of Table 
XVII and that given in the preceding chapter furnish all 
the information that is necessary for the calculation of 
balanced rations. Two concrete examples are here given 
to show the method and the operations involved in such 
calculations. 

Example 1, The single feed, oats, is nearly a balanced 
ration for horses; its nutritive ratio is therefore calculated as 
the simplest illustration. 

The Wolff-Lehmann standard shows that a ration for a 
horse consists of 24 pounds of dry matter. From Table 
XVII we find that 89.6 per cent of oats is dry matter. 
Hence, 24X100-^89.6 = 26.8 pounds, or 26.8 pounds of 
oats must be fed to furnish 24 pounds of dry matter. There- 
fore, calculating the nutritive ratio of 26.8 lbs. of oats, we 
have the values shown in Table XVIII. 

In the calculation, the pounds of feed are multiplied by 
the percentage of each nutrient and the result is given in 
the third column of the table. This result is then multiplied 
by the coefficient of digestibility, or per cent of digestible 
material, and the amount of digestible nutrients are placed 
in each case under the proper head in the table. The diges- 
tible carbohydrates are added to 2.25 times the digestible 
fat (because fat is estimated to have 2.25 times the heat- 
giving power of carbohydrates) and the sum is divided by 
the digestible protein. The quotient gives the nutritive 
ratio compared with the digestible protein as the unit. 



FEEDS— THE CALCULATION OF RATIONS 



195 



TABLE XVIIL— THE NUTRITIVE RATIO OF 26.8 POUNDS OF 

OATS 





03 
O 

H 

"o 

a 
<u 
O 

0> 

Ph 


d 

o 

d 

03 

6 


3 

'£> 

<x> 

M 

5 

a 

O 

u 


Digestible Nutrients. 


,£ 


Nutrient. 


CD 
>> 

Q 


a 

"8 

o 

3 

o 


03 

a> 
03 

-S 

>> 

O 
XI 

03 

o 


-J 

03 


sat 

£.ss 


Dry matter 


89.6 
11.4 
10.8 
59.4 

4.8 


24.0 
3.05 
2.89 

15.92 
1.29 


77 
31 
77 
89 


24.0 


2.35 


0.90 
12.26 


1.15 




Crude protein. . . 




Crude fiber 




Nitrogen-free extract. . . . 
Fat 








Ration 








24.0 
24.0 


2.35 
2.0 


13.16 
11.0 


1.15 
0.6 


1:6.7 


Wolff-Lehmann 




1:6.2 



Thus in this case, 



89.6 

loo 



X26.8 pounds = 24 pounds, the 



amount of dry matter; 



11.4 

loo 



X 26 . 8 = 3 . 05 pounds protein, 



etc. Of this protein, 77 per cent or T Vo is digestible ; hence 
T 7 o 7 oX3.05 pounds = 2. 35 pounds digestible protein, simi- 
larly, T VoX2.89 pounds = 0.90 pound digestible crude 
fiber, etc., etc. The nutritive ratio = digestible protein: 
(digestible carbohydrates + 2.25 X fat) = 2.35 : (0.90 
+ 12. 26+2. 25X1. 15) = 1 : 6.7. 

The foregoing calculation shows that oats contain a 
nutritive ratio well suited to the needs of the horse, but 
that the proper amount of digestible dry matter contains 
too large an amount of nutrients ; therefore, even with oats, 
some hay should be fed to give bulk. When this is done, 
the amount of oats fed will be reduced. 

Example 2. The calculation of a ration for a dairy 
cow giving 27.5 pounds of milk will serve as an example of 
a more complicated problem. Suppose that it is proposed 



196 



CHEMISTRY OF FARM PRACTICE 



to feed 4 pounds of cottonseed meal, 6 pounds of wheat 
bran, 10 pounds of alfalfa hay, and 40 pounds of silage; 
the results based on the percentages given in table XVII 
and calculated as in Example 1, are tabulated in table XIX. 

TABLE XIX.— AN UNCORRECTED RATION 





Lbs. 

as 

Fed. 


Dry 

Matter. 


Digestible Nutrients. 






Pro- 
tein. 


Fiber 

and 

N-Free 

Ext. 


Fat. 


Nutri- 
tive 
Ratio. 


Cottonseed meal. . . 

Wheat bran 

Alfalfa hay 

Corn silage 


4.0 

6.0 
10.0 

40. 


3.72 

5.29 

9.34 

10.56 


1.28 
0.71 
1.14 
0.56 


f 0.15 

( 0.76 
J 0.22 
j 2.29 
| 1.35 

j 2.58 
j 1.59 

[ 3.87 


| 0.39 
| 0.15 
1 0.08 
1 0.28 




Total 


60.0 


28.91 
32.00 

- 3.09 


3.69 
3.30 

+0.39 


12.81 
13.00 

-0.19 


0.90 
0.80 

+0.10 


1:4 


Wolff-Lehmann . . . 
(From Table XVI.) 


1:4.5 



An inspection of the results in Table XIX shows that the 
protein content is more than is required, while the fat and 
carbohydrates are about right in amount. It is desirable to 
keep the total dry matter lower, if possible, than the Wolff- 
Lehmann figure. The correction of this ration can be 
accomplished by reducing the cottonseed meal and increasing 
the bran or by reducing the alfalfa hay and substituting a 
hay cheaper and less nutritious. In sections where cotton- 
seed meal is cheap, its reduction will not be desirable; but, 
in sections where it is expensive, 1| pounds of it may be 
replaced with an equal weight of corn meal. Table XX 
shows such a correction. 



FEEDS— THE CALCULATION OF RATIONS 197 



TABLE XX.— A CORRECTED RATION FOR A DAIRY COW 
PRODUCING 27.5 LBS OF MILK 





Pounds. 


Digestible Nutrients. 






Feed. 


Dry 

Matter. 


Pro- 
tein. 


Fiber 

and 

N-Free 

Ext. 


Fat. 


Nutri- 
tive 
Ratio. 


Cottonseed meal. . . 

Corn meal 

Wheat bran 

Alfalfa hay 

Corn silage 


2.5 
1.5 
6.0 

10.0 

40.0 


2.33 
1.28 
5.29 

9.34 

10.56 


0.80 
0.09 
0.71 

1.14 

0.56 


f 0.06 

( 0.48 

0.95 

J 0.22 

j 2.29 

1.35 

2.58 

1.59 

3.87 


} 0.24 

0.05 

1 0.15 

j 0.08 

| 0.28 




Totals 

Wolff-Lehmann . . . 
(From Table XVI.) 


60.0 


28.80 
32.00 

-3.20 


3.30 
3.30 

+ .00 


13.39 
. 13.00 

+ 0.39 


0.80 
0.80 

+ .00 


1:4.6 
1:4.5 



The substitution of corn meal in place of 1J pounds of 
the cottonseed meal served to balance the ration very 
satisfactorily. 

These type calculations, problems 1 and 2, show the steps 
involved in calculating rations. Considerable liberty may 
be taken with the nutritive ratios in order to use cheap feeds, 
but they serve as a guide and should be followed as closely 
as possible for best results. 



CHAPTER XIX 

MILK AND ITS PRODUCTS 

146. Milk. Milk contains water, fat, casein, albumin, 
milk-sugar, and mineral salts in proportions especially 
suited to the young of the mammal producing it. Table 
XXI shows the average composition of the milk of a num- 
ber of mammals : 

TABLE XXL— THE COMPOSITION OF VARIOUS MILKS 



Mammal. 


Per Cent 

of 
Water. 


Per Cent 

of Total 

Solids. 


Per Cent 

of 
Proteids. 


Per Cent 

of 

Fat. 


Per Cent 

of 

Sugar. 


Per Cent 

of 

Ash. 


Human 


88.00 

87.25 
86.60 
.81.30 
90.00 
89.60 
67.80 
41.10 


12.00 
12.75 
13.40 
18.70 
10.00 
10.40 
32.20 
58.90 


1.50 
3.50 
4.60 
6.30 
1.90 
2.20 
3.10 
11.20 


3.50 
4.00 
4.30 
6.80 
1.10 
1.60 
19.60 
45.80 


6.80 
4.50 
4.00 
4.80 
6.70 
6.10 
8.80 
1.30 


0.20 


Cow 


0.75 


Goat 


0.60 


Ewe 


0.80 


Mare 


0.30 


Ass 


0.50 


Elephant 


0.70 


Porpoise 


0.60 







147. Milk from Different Breeds of Cattle. The 

nutritive ingredients of milk are combined in such propor- 
tions that it serves excellently as a part of the diet of adults, 
and its products, butter and cheese, are widely used and 
highly nutritious foods. For the production of butter, the 
content of fat in the milk is of prime importance, provided 
that the yield of milk is not sacrificed to this end. In table 
XXII are shown the differences in composition of milk of 
different breeds of cattle. 

198 



MILK AND ITS PRODUCTS 



199 



TABLE XXII.— A COMPARISON OF THE COMPOSITION OF 
MILK FROM DIFFERENT BREEDS 



Breed. 


Per Cent 

of 
Water. 


Per Cent 
of Total 
Solids. 


Per Cent 

of 
Proteins. 


Per Cent 

of 

Fat. 


Per Cent 

of 

Sugar. 


Per Cent 

of 

Ash. 


Jerseys 


85.66 
87.55 
87.88 


14.34 
12.45 
12.12 


3.96 
3.27 

3.28 


4.78 
3.65 
3.51 


4.85 
4.80 
4.69 


75 


Shorthorns 

Holstein-Friesians . 


0.73 
0.64 



The Jersey breed is noted for the production of rich 
milk, cream, and butter. The Holstein-Friesian breed is 
highly specialized for the production of a large quantity of 
milk. This milk serves well for the manufacture of cheese, 
and where the per cent of fat meets city inspection require- 
ments, a dairy of this breed will prove especially profitable 
on account of the large yield of milk. The rcilkiDg strains 
of the Shorthorn breed are desirable both for the production 
of the home milk supply in rural districts and as heef animals. 

148. Danger from Infected Milk. Before being used 
for feeding infants, cows' milk must be changed in com- 
position to make it more nearly conform to the composition 
of human milk. This is accomplished by diluting it with 
water to reduce the protein and fat and by adding sugar. 

Great care should be taken with the milk used for chil- 
dren. It. is estimated that 500,000 deaths occur annually 
in the United States from diseases and derangements due 
to infected or bad milk. Milk is an excellent medium for 
the growth of harmful bacteria, and every precaution should 
be taken to assure its purity. Where milk is purchased, 
there is danger from watering, leading to a lowering of its 
nutritive value, and from preservatives. Even when pro- 
duced at home, every care should be exercised to see that 
the cows are healthy and that no poisonous weeds are fed. 
Any unusual appearance or odor of milk should be regarded 
with suspicion. 

An abnormal color in milk is easily noticeable. Blue color 



200 



CHEMISTRY OF FARM PRACTICE 



may be due to microorganisms; yellow color to chrcmogenic 
organisms or to the fact that rhubarb has been eaten; 
red color to the eating of rhubarb, madder, and also to several 




groups of bacteria, and green color is caused by pus-forming 
bacteria. Any unusual color is to be regarded with instant 
suspicion, and such milk should not be used until the source 
and harmless character of the color is established. 



MILK AND ITS PRODUCTS 201 

Typhoid fever, scarlet fever, diphtheria, foot and mouth 
disease, cowpox, anthrax, and glandular tuberculosis are 
some of the forms of diseases that are known to be occasioned 
by the use of infected milk. 

Milk is so liable to become a source of danger as a food 
that all well-governed cities have placed the milk supply 
under government inspection. In many cases this control 
is so efficient that milk obtained in the city is safer and better 
than that obtained in the country. To pass the inspection 
the farmer is compelled to deliver a purer and higher grade 
of milk for city markets. The New York Board of Health 
have ruled that milk containing more than 88.5 per cent 
of water or less than 3 per cent of fat or less than 11.5 
per cent of solids cannot be offered for sale legally in that city. 
The Boston Board of Health prohibits the sale of milk con- 
taining more than 500,000 bacteria per cubic centimeter or 
which is delivered at a temperature higher than 50° F. 

149. Preservatives. Milk becomes infected a short time 
after production. If the use of the milk as a food is delayed, 
bacteria increase to inconceivable numbers. At the temper- 
ature of the human body (98.6° F. or 36° C.) one bacterium 
in milk will multiply to 75,000 in twenty-four hours. If the 
temperature is reduced to 50° F. bacteria will increase very 
slowly, if at all. All bacteria are not dangerous; some 
species are friendly, aiding in the processes of digestion and 
assimilation. There are three ways of controlling the num- 
ber of bacteria: First, by preventing as far as possible 
infection, by healthy cows, cleanly methods of production 
and handling and control of temperature; second, by treat- 
ing the milk by sterilization or pasteurization and then guard- 
ing against further infection; third, by adding to the milk 
some preservative which is germicidal. The last of these 
methods is to be condemned. Some preservatives are 
harmful, and all serve to preserve the milk by producing con- 
ditions that are not conducive to easy digestion. Formalin, 
which is a 40 per cent solution of formaldehyde (HCHO), 



202 



CHEMISTRY OF FARM PRACTICE 



is used in proportions of from 1 part formalin, 20,000 parts 
milk or to 50,000 parts milk, the smaller quantity will 
preserve milk for two days. Sodium carbonate (Na2C03) 




1 

wo 

I 

CO 
■JD 

6 



and magnesium carbonate (MgCOa) serve to neutralize 
acidity and to improve the appearance of the milk. Potas- 
sium carbonate (K2CO3), borax (Na2B 4 07) and boracic acid 
(H3BO3) are used as preservatives. They tend, however, 



MILK AND ITS PRODUCTS 203 

to retard the separation of the cream. Sodium benzoate 
(CeH^COONa), salicylic acid (C6H4OHCOOH), potassium 
nitrate (KNO3), calcium peroxide (Ca02) and hydrogen 
peroxide (H2O2) in milk are all harmful. The fluorides, 
fluosilicates and fluoborates are dangerous poisons. Milk 
that is properly produced will keep as long as is necessary 
without preservatives, and the use of preservatives but 
serves to hide filthy handling and bad management. 

The pasteurization of milk consists in keeping it at a 
temperature between 63° C. and 75° for at least twenty min- 
utes, then rapidly chilling the milk. The necessity for 
pasteurizing milk should be avoided, because lecithin, which 
is beneficial to growing children, is destroyed, and also 
because enzymes which are helpful to digestion are killed. 
Pasteurization serves to kill disease-producing bacteria 
when present. Imperfect pasteurization of milk is, how- 
ever, a source of danger, because incomplete heating kills 
the harmless lactic acid bacteria, while the dangerous putre- 
factive bacteria may not be affected. Such milk will keep 
from souring for a long time, and so the buyer, deceived by 
the absence of souring, may use milk impregnated with dis- 
ease-producing germs. 

150. The Detection of Formaldehyde in Milk. The pres- 
ence of formaldehyde in milk may be detected as follows: 

Method 1: Sulphuric Acid Test: Place 5 to 10 cubic 
centimeters of the milk in a large test-tube, or clean bottle, 
and add one-half the amount of commercial sulphuric acid, 
carefully pouring the acid down the side of the tube or bottle 
so that the milk and acid are not mixed. As the acid is 
heavier than the milk, it will sink to the bottom of the vessel. 
If a violet zone is formed at the junction of the two liquids, 
formaldehyde is present. The sulphuric acid should 
contain some iron; if chemically pure acid is used, a little 
ferric chloride must be added. 

Method 2: Hydrochloric Acid Test. First prepare the 
acid for the test by adding two drops of ferric chloride 



204 CHEMISTRY OF FARM PRACTICE 

solution to 50 cubic centimeters of the concentrated acid 
(sp. gr. 1.20). Place 10 cubic centimeters of the milk in 
a casserole or a porcelain evaporating dish, add an equal 
volume of the prepared acid and heat the mixture nearly 
to boiling. While heating, swirl the contents of the dish 
gently so as to break up the curd. 

The presence of formaldehyde is indicated by a violet 
color varying in intensity with the amount of formaldehyde 
present. If no lormaldehyde is present, the mixture turns 
brown. 

151. Detection of Boracic Acid. To 10 cubic centimeters 
of the milk add 6 drops of concentrated hydrochloric acid 
and mix thoroughly. Dip a strip of turmeric paper in the 
mixture and dry the paper by wrapping it about a test-tube 
which contains boiling water. In the presence of boracic 
acid or a borate the turmeric paper, which is a reddish-brown 
color, will turn to a greenish-black color upon treatment 
with a drop of sodium hydroxide. 

152. Testing Milk for Per Cent of Fat. The Babcock 
test is a rapid, accurate, and inexpensive method for deter- 
mining the amount of fat in milk and other dairy products. 

For making the test, a centrifuge, two forms of which are 
shown in Fig. 67 and the test bottles, pipette for measuring 
the milk, acid measure, brush for cleaning the bottles, and 
sulphuric acid, shown in Fig. 68, are required. 

The neck of the test bottles are marked with a graduated 
scale, each small division representing two-tenths of 1 
per cent of fat. Every fifth division is a long one and repre- 
sents 1 per cent. In making the test 17.5 cubic centimeters 
of milk, which weigh 18 grams, are first slowly run into the 
bottle by means of the pipette, holding the pipette at an 
angle as is shown in Fig. 69. This method of running in the 
milk prevents overflowing due to the stopping of the outlet 
for air. 

The reason for the use of 18 grams of milk is that the neck 
of the test bottle is graduated to hold just 2 cubic centi- 



MILK AND ITS PRODUCTS 



205 




Fig. 67. — Centrifuge for the Babcock test. 




Fig. 68. — Additional apparatus for the Babcock test. 



206 CHEMISTRY OF FARM PRACTICE 

meters in the graduated portion. The specific gravity of 
milk fat is 0.90, therefore the amount required to fill the 
graduated portion is 0.90X2=1.8 grams, which is 10 per 
cent of 18 grams of milk. The milk pipette holds 17.6 
cubic centimeters, but will deliver 17.5 cubic centimeters 
of milk because .1 cubic centimeter will adhere to the sides 
of the pipette. The acid cylinder is graduated to deliver 
17.5 cubic centimeters. 

The sulphuric acid used for the Babcock test should be 

i ~ 




S 






Fig. 69. — Placing the milk in a test bottle. 

of a specific gravity of between 1.82 and 1.83 at 60° Fahren- 
heit. Commercial acid, which is good enough for this test, 
is bought at a density of 1.84. To dilute this for use in 
the dairy, 1000 cubic centimeters of the acid should be 
poured into 45 cubic centimeters of water, or 100 cubic centi- 
meters of water for every ordinary 5-pin t bottle of acid. 
In reducing the specific gravity of sulphuric acid, always 
pour the acid into water, and never pour water into the acid. 



MILK AND ITS PRODUCTS 



207 



After dilution, the acid must be cooled to 60° F. before being 
used in the test. 

The details of the test are as follows: Mix thoroughly 
the sample of milk, which should be at a temperature of 
about 60° F, Quickly fill the pipette to the mark with milk, 




Fig. 70. — Appearance of completed test. 

and run the milk into the test bottle. Fill the acid measure 
to the mark with the sulphuric acid and pour the acid cau- 
tiously into the test bottle. Mix the milk and acid 
thoroughly by giving the test bottle a rotary motion. Let 
the bottle and contents stand from two to five minutes and 
then mix again. 



208 CHEMISTRY OF FARM PRACTICE 

Put the test bottles in the centrifuge and whirl for four 
or five minutes at a speed of 600-1200 revolutions per min- 
ute. Then add hot water to fill the test bottle to the neck 
and whirl again for one minute; next add hot water to near 
the top of the graduated portion and whirl one minute 
more. 

The reading of the per cent of fat should be taken at 
about 130° F. This is best accomplished by means of a 
pair of dividers. The appearance of the test bottle after 
completed test is shown in Fig. 70. 

The results obtained in this determination are due to the 
actions of strong sulphuric acid and the use of centrifugal 
force. The action of the acid is threefold: It destroys 
the adhesive force exercised by the casein, albumin, sugar, 
and salts present in the milk; the mixture of sulphuric acid 
and milk generates heat, which causes the fat globules to 
run together and makes their separation from the mass 
comparatively easy; third, the weight of the sulphuric 
acid increases the specific gravity of the non-fatty materials, 
causing the lighter fat the more readily to rise to the sur- 
face. The completion of the separation of the fat is accom- 
plished by the use of centrifugal force when the bottle con- 
taining the mixture is whirled in a suitable apparatus, which 
may be run either by hand or by power. 

153. Determination of Specific Gravity. The normal 
specific gravity of milk from a herd usually falls between 
1.030 and 1.034. The specific gravity of milk is quickly 
determined by taking the reading of a lactometer floating in 
the milk. The lactometer is a specialized form of a hydrom- 
eter. The Quevenne lactometer has a scale graduated 
from to 15 to 40°, corresponding to specific gravities from 
1.015 to 1.040. The milk should be tested at a temperature 
ranging from 55° F. to 60° F., adding a correction of 1° 
(equivalent to 00.001 specific gravity) to the reading for 
each degree F. above 60° F. and subtracting 1° for each 
degree F. below 60° F. 



MILK AND ITS PRODUCTS 209 

The addition of water to milk lowers the specific gravity, 
while the skimming of cream from the milk raises the specific 
gravity. It is therefore possible, by skillful manipulation, 
for dishonest handlers both to water and to skim the milk 
so as to leave it with a specific gravity corresponding to 
normal milk. Such tampering, however, will give the milk 
a suspicious appearance, and if the percentage of solids, 
not fat, falls below 7.7, such milk may be considered adulter- 
ated. 

154. Determination of Water and Total Solids. To de- 
termine the water and total solids in milk the procedure is 
as follows: Clean and weigh crystallizing dishes with a 
capacity of about 100 cubic centimeters or, if available, a 
platinum dish 3 inches in diameter. Weigh these with small 
glass rods in each for use in breaking the surface film so 
as to increase the rate of drying. With the pipette run 5 
cubic centimeters of the well-mixed milk sample into the 
dish and obtain the exact weight of the milk. Dry it in an 
oven at 100° C. or on the surface of a steam bath to constant 
weight. Two or three hours ought to be sufficient for com- 
plete drying. Weigh and compute the dried residue as 
total solid and the loss by evaporation as water. If the 
ash is not to be determined, an excellent dish for the deter- 
mination of water and total solids is the shallow cover of 
a tin baking-powder box. 

155. Determination of Ash. If a platinum or a porcelain 
dish was used for the determination of water and total solids, 
the dried residue from that process may be ashed by heating 
cautiously to a temperature just below red heat till the ash 
is white or of uniform light gray color. When the weight 
is constant, compute the residue as ash. 

156. Butter. Butter, in addition to butter fat, con- 
tains water, curd and salt. In making butter, where the 
work is carefully conducted, the butter procured is 
usually one-sixth more than the butter fat contained in the 
cream. 



210 



CHEMISTRY OF FARM PRACTICE 



TABLE XXIII.— COMPOSITION OF CREAMERY BUTTERS. 

(Wisconsin Experiment Station) 



Highest 
Lowest. . 
Average, 



Per Cent 

of 

Water. 



17.03 

9.18 

12.77 



Per Cent 

of 

Fat. 



87.50 

77.07 

83.08 



Per Cent 

of 

Curd. 



2.45 
0.36 
1.28 



Per Cent 

of Salt 
and Ash. 



4.73 
1.30 

2.87 



Sum of 

Water, Curd, 

Salt, and 

Ash. 



22.95 
12.50 

16.92 



Good butter should contain at least 80 per cent fat and, 
preferably, it should run 83 per cent fat. Genuine butter 
may usually be distinguished from oleomargarine without 
any special test. Most oleomargarine is more solid than 
butter and is brittle and hard when cold. When soft, it is 
smeary and shows no grain. 

Process butter is manufactured from old or poor butter. 
It is first melted and treated with steam to carry off any of 
the disagreeable acids which have resulted from the decom- 
position of the fat. It is then mixed with milk, solidified, 
salted and worked. Process butter has properties similar 
to those of oleomargarine. 

A simple test for butter is to heat it to boiling, carefully, 
in a tablespoon. Good butter boils with little noise and 
spatter and produces an abundance of foam. Oleomar- 
garine and process butter boil with considerable spattering 
and produce little foam. The " meaty " odor when hot 
is characteristic of the animal fats used in oleomargarine. 

157. Cheese. Cheese is made by coagulating milk 
when heated. American cheddar cheese is made by heating 
the milk to 80° Fahrenheit and adding a small amouut of 
rennet extract. The casein in the milk is coagulated by 
the rennet and holds the fat. The green cheese analyzes 
about 37 per cent water, 34 per cent fat, 24 per cent pro- 
teids, the other 5 per cent consisting of mineral salts, lactic 
acid, and milk sugar. Most of the milk sugar and albumin 
is drawn off in the whey. 



MILK AND ITS PRODUCTS 211 

158. Condensed Milk. Condensed milk is manufactured 
either from whole or partly skimmed milk. In some cases, 
sugar is added to improve its keeping qualities. Condensed 
milk should contain not less than 10 per cent fat, and must 
be free from preservatives. 



CHAPTER XX 
INSECTICIDES, FUNGICIDES AND DISINFECTANTS 

159. Two Classes of Injurious Insects. The insects 
which are injurious to growing or stored crops may be 
separated into two main classes : insects that bite, and those 
that suck. Different remedies must be used in combating 
each class. Among the most common biting insects are the 
codling moth, potato bettle, th«e flea beetle, the grass- 
hopper, the tussock, brown tail, and gypsy moths, the plum 
curculio, and the various caterpillars. The biting insects 
are destroyed by spraying the plants eaten with some 
poisonous material that will be taken by the insect with its 
food. The materials commonly used for this purpose are 
compounds of arsenic which has decided toxic effects. Some 
of these substances are arsenate of lead, Paris green, green 
arsenoid, London purple, and arsenate of lime. The last 
named is a product recently put on the market. 

Sucking insects draw the plant juices from the leaves 
and the bark; the most common are plant lice, the Chinch 
bug, San Jose scale, scurfy scales, etc. They are killed by 
materials that close their breathing pores, fill the surround- 
ing atmosphere with poisonous fumes, or kill by reason of 
their caustic properties. The following materials are used 
for this purpose: kerosene emulsion, soaps, lime-sulphur 
mixtures, nicotine sulphate solutions, carbon bisulphide, 
and hydrocyanic acid gas. 

160. Injurious Fungi. Injurious fungi are minute 
vegetable organisms that attack living tissue. The fungi- 
cides include Bordeaux mixture (made from milk of lime and 
copper sulphate), lime-sulphur, sulphur, copper sulphate, 
ammoniacal copper carbonate, and formaldehyde solutions. 

212 



INSECTICIDES, FUNGICIDES AND DISINFECTANTS 213 

The compounds of copper have decided poisonous effects 
upon the lower organisms. 

161. Insecticides for Biting Insects. Lead arsenate 
may be purchased in the form of a thick paste or dry powder. 




Fig. 71. — Pail spray for small herds. (Farmers' Bulletin, U. S. 

Dept. Agr.) 

It is prepared by the action of lead nitrate or lead acetate 
on crystallized disodium hydrogen arsenate. It contains 
little or no soluble arsenic and, for this reason, is especially 
applicable to plants with tender foliage. Lead arsenate is 
applied in suspension in water or in combination with fungi- 
cides by means of a spray, usually at the rate 2 to 7 pounds 



214 CHEMISTRY OF FARM PRACTICE 

of the paste or half of that quantity of the powder, to 50 
gallons of the spray solution. Whether used as paste or 
powder, the lead arsenate should first be stirred or ground 
very thoroughly in a small amount of the spray solution, 
and gradually diluted until a very smooth paste is formed. 

Paris green is a mixture of copper acetate and copper 
arsenite. It is somewhat more soluble than is lead arsenate 



Fig. 72. — Knapsack sprayer. The handle can be removed and the 
tank carried in the hand instead of on the back, if desired. (Far- 
mers' Bulletin 243, U. S. Dept. Agr.) 

and, for this reason, it may injure tender foliaged plants. 
Paris green has been largely superseded as an insecticide by 
lead arsenate. It may be applied dry by diluting with from 
10 to 50 parts of land plaster, flour or road dust. When used 
in this way, there is danger of burning tender foliage. A 
solution of 1 pound of Paris green and 3 pounds of stone 
lime in 100 to 250 gallons of water, depending on the foliage, 
is advised. 



INSECTICIDES, FUNGICIDES AND DISINFECTANTS 215 

Green arsenoid is an insecticide similar to Paris green, and 
applied in the same manner, but is less used. 

London purple is a by-product of the manufacture of 
anilin dyes. It is composed of calcium arsenate and cal- 
cium arsenite together with an organic dye residue. Lon- 
don purple is quite variable in composition, and is very 
little used. 

162. Insecticides for Sucking Insects. Kerosene emulsion 
is prepared by emulsifying soap. A good quality of laundry 
soap is satisfactory. Two to four pounds of soap and 5 to 10 
gallons of kerosene to 50 to 100 gallons of spray solution are 
the usual proportions. The soap should be dissolved in 
from 5 to 10 gallons of hot water, placed, together with the 
kerosene, in the spray barrel, then emulsified by pumping 
air through the spray rod into the spray solution. Kero- 
sene-emulsion should be used promptly after preparation. 

Soaps are sometimes used to destroy soft-bodied insects. 
Fish-oil soap is one of the best and most commonly used 
soaps for this purpose. Potash soap is better than soda, 
soap. The soap is more easily dissolved in hot water, and 
the solution applied by means of the spray pump. A 
solution of 2 pounds of rosin fish-oil soap in 50 gallons of 
water is often used asa " sticker " for fungicides with poor 
adhesive qualities. 

Lime-sulphur mixtures are prepared by boiling sulphur 
with milk of lime. The chief constituents of these mixtures 
are poly sulphides of calcium, the tetra- and the penta- 
sulphide being most desired, and calcium thiosulphate. 

Nicotine solutions are obtained from decoctions of tobacco, 
the nicotine being the active agent. One-half pound of 
tobacco is steeped in boiling water and then diluted to 
5 or 10 gallons. These solutions are used chiefly for the 
control of plant lice. 

Nicotine sulphate solutions, such as Black Leaf — 40 are 
used extensively and have replaced kerosene emulsion for 
aphis. 



216 CHEMISTRY OF FARM PRACTICE 

Carbon bisulphide (CS2) when partially decomposed by- 
standing is a vile-smelling liquid which vaporizes at ordinary 
temperatures. Its use in the field is limited, being mainly 
confined to the control of certain root-infesting plant lice. 
It is extensively used for the control of insects in granaries. 
In tight cribs it is best applied on top of grain or corn at 
the rate of 6 pounds to 100 bushels applied when the tem- 
perature is above 65° F. 

Hydrocyanic acid gas (HCN) is prepared by treating 
potassium cyanide with excess of sulphuric acid; 2KCN 
+H2S04 = 2HCN+K2S04. This gas is very poisonous 
and its use is not advised. When used, the proportion of 
1 pound of the potassium cyanide, 2 pounds of sulphuric acid 
and 4 pounds of water gives a rapid evolution of the gas. 
Care must be exercised not to inhale the extremely poisonous 
fumes. 

163. Fungicides. Bordeaux mixture is prepared from 
copper sulphate (CuSCU) and calcium hydrate (Ca(OH)2). 
The most common proportions are 4 pounds of copper sul- 
phate and 4 pounds of quicklime to 50 gallons of water. 
The copper sulphate should be dissolved and made up to 
25 gallons of water. The lime should be carefully slaked 
with water and made to twenty-five gallons. Pour the 
dilute solutions into the spray barrel, stirring vigorously 
and use while fresh. The above proportions may be widely 
varied to meet special needs. 

Copper sulphate is difficult to dissolve. The solution 
may best be accomplished by putting the powdered crystals 
in a small bag which is suspended over night in the water, 
near the surface. The copper sulphate solution, being more 
dense than water, sinks, leaving the copper sulphate crystals 
in constant contact with an unsaturated solution. Powdered 
portions of the crystals will dissolve rapidly in hot water. 

Lime-sulphur has already been discussed. As a fungicide 
for plants in foliage, the commercial product, 32° Baume, is 
applied at the rate of 1 to 2 gallons in 50 gallons of water, 



INSECTICIDES, FUNGICIDES AND DISINFECTANTS 217 

depending upon the liability of the plant to lime-sulphur 
injury. 

Self-boiled lime-sulphur is prepared from quick-lime (CaO) 
and sulphur flour. The sulphur is put in suspension through 
the agency of the slaking lime, very little chemical union of 
lime and sulphur probably occurring. The usual proportions 




Fig. 73. — Barrel spray pump with hose and bamboo extension rods 
for orchard spraying. (Farmers' Bulletin 243, U. S. Dept. Agr.) 



are 8 pounds of lime and 8 pounds of sulphur in 50 gallons 
of water. The process is carried out to best advantage 
when four times the above quantities are used. This spray 
is especially adapted to use on tender-foliaged plants. 

Finely divided sulphur in suspension is largely replacing 
self-boiled lime-sulphur and ordinary lime-sulphur. Several 
proprietary preparations of this nature are on the market. 



218 



CHEMISTRY OF FARM PRACTICE 



They are more expensive than self-boiled lime-sulphur, and 
about equally effective. Their advantages are that they are 
more easily prepared and that they leave less residue upon 
both fruit and foliage. 




Fig. 74. — Gasoline, power spray. (Bulletin 243, U. S. Dept. Agr.) 



Copper sulphate (CuSO±) is used as a dormant spray for 
certain types of fungus diseases of plants. A notable 
example of this is its use in connection with the control of 
peach leaf curl. It is one of the most toxic of fungicides, 



INSECTICIDES, FUNGICIDES AND DISINFECTANTS 219 

but its period of activity is of short duration, due to the 
fact that it is quickly washed off the plant. Copper sulphate 
is very successfully used for the destruction of algae in water. 

Ammoniacal copper carbonate (Cu(NH 3 )4C03) is used 
in special cases on ornamental plants and on certain fruits 
just before ripening, w r here residues from other sprays 
would be objectionable. The chief objections to this prep- 
aration are its relatively high toxicity to the host plant, 
its cost, and the difficulty of its preparation. 

Formaldehyde solutions (CH 2 0) are chiefly used for the 
treatment of seeds and vegetable reproductive materials, 
as tubers, to rid them of disease before planting. The 
solution is prepared by adding 1 pint of formalin to 30 gal- 
lons of water. 

164. Common Disinfectants. Disinfectants are used to 
destroy organisms that bring on disease, decay, and dis- 
agreeable odors. There are several common and effective 
kinds. In handling disinfectants great care should be exer- 
cised, as many are very poisonous. 

Lime. Unslaked lime (CaO) and water-slaked lime 
(Ca(OH)2) are the cheapest and most easily obtained dis- 
infectants. Air-slaked lime (CaCOs) has no disinfecting 
properties except that due to absorption. Lime that is to 
be used for disinfecting purposes should be kept in recep- 
tacles that are tight enough to exclude air. It is best applied 
in the form of milk of lime, prepared as follows: Treat 
a lump of quick-lime in a covered vessel with water until 
a creamy liquid is formed. This should be kept in an air- 
tight receptacle when not in use. Quicklime may be pul- 
verized and sprinkled on dry; this form is especially useful 
in closets, replacing earth. 

Chlorinated Lime (Bleaching powder, C'aCT^O). This 
material is prepared by showering slaked lime powder 
through chlorine gas. It is a white powder, which decom- 
poses slowly on exposure to moisture, giving off hypochlorous 
acid, which is the substance that gives the characteristic 



220 CHEMISTRY OF FARM PRACTICE 

odor to bleaching powder. It should be kept in sealed con- 
tainers. Chlorinated lime is prepared for use by mixing in 
the proportion of 6 ounces of the powder to each gallon of 
water. It is largely used for the disinfection of refuse, 
stock-pens, or cars, and is the most efficient disinfectant. 
It has a bleaching effect on fabrics when there is need of 
concentrated effect; the chlorinated lime may be treated 
with dilute acid. 

Formaldehyde. Formaldehyde (HCHO) is commonly 
purchased under the name formalin, which is a solution con- 
taining about 40 per cent formaldehyde. It may be used 
for disinfecting purposes either as a liquid or as a gas. A 
5 per cent solution of formalin is considered to be superior 
to carbolic acid of the same strength, as a disinfectant. 
Formaldehyde is peculiarly effective as a disinfectant, as it is 
an unstable compound which on the one hand is easily re- 
duced to methyl alcohol by the addition of hydrogen or of 
reducing agents, which it abstracts from the organism which 
needs disinfection, and on the other hand, it is easily oxidized 
into formic acid by the addition of oxygen, which it takes from 
the substance to be disinfected — in either case sterilizing the 
infecting material. 

These opposing actions are represented by the following 
equations : 

HCHO+H 2 = CH3OH 

Formaldehyde Methyl alcohol 

HCHO+O = HCOOH 

Formaldehyde Formic acid 

When disinfecting with gaseous formaldehyde, it is neces- 
sary to close tightly the place to be disinfected in order that 
the concentrated gas may be in contact with the infected 
material for some time and the temperature should be warm. 
The gas may be produced from formalin in several ways, 
but the chemical means are usually most convenient. The 
various methods are: heating under pressure, heating with- 



INSECTICIDES, FUNGICIDES AND DISINFECTANTS 221 

out pressure, spraying and by an oxidizing agent. The 
last two are ordinarily used. When spraying is resorted to, 
the compartment should be kept closed for at least twenty- 
four hours. An ounce of formalin is required to each 
100 cubic feet, therefore a room 10 feet square and 10 feet 
high would require ten ounces. The formalin is sprayed 
on sheets hung in the room. 

The gas is readily liberated by several chemicals, but the 
use of potassium permanganate has found most favor. The 




Fig. 75.— Making Bordeaux mixture. The two men pour together 
the diluted lime milk and the bluestone solution into a barrel or 
spray tank and stir well. (Bulletin 243, U. S. Dept. Agr.) 

proportion which is most effective seems to be 6 parts of 
formalin to 5 parts of potassium permanganate. For dis- 
infecting 1000 feet of space, 20 ounces of formalin and 16f 
ounces of potassium permanganate are required. The crystals 
of potassium permanganate may be placed on the bottom 
of an ordinary dishpan and the formalin poured on quickly 
in order that the person so engaged may make a rapid exit. 
Some of the formaldehyde is oxidized to formic acid by the 
permanganate and this generates heat enough to drive the 
remainder out as a gas. The compartment should be kept 



222 CHEMISTRY OF FARM PRACTICE 

closed for not less than twelve hours. The temperature of 
the room should not be less than 65° F. for the treatment 
to be effective. It is well to sprinkle the floor and other 
objects not harmfully affected by water, before the treat- 
ment, as it is more effective in a damp atmosphere. 

Sulphur. Barns and other outbuildings may be more 
cheaply but not as thoroughly disinfected with sulphur 
fumes. These fumes bleach fabrics and discolor some paints, 
for which reason their use is not always to be recommended. 
Use not less than 4 pounds of sulphur to each 1000 cubic feet. 
Break the roll sulphur into small pieces and put them into 
an iron pot which should be set in a tub containing a few 
inches of water as a preventive of fire. Pour alcohol on the 
sulphur and ignite. If possible, keep the compartment closed 
for twelve hours. 

Carbolic Acid. Carbolic acid or phenol (C G H 5 OH) has 
been extensively used as a disinfectant for years. It is 
poisonous and should be carefully handled. Pure carbolic 
acid is a solid at ordinaiy temperatures and crystallizes into 
long pink or white needles. It is often sold in the liquid 
form, which is prepared by adding 1 part of water to 9 
parts of the crystals. Carbolic acid used in the proportion 
of 1 part of acid to 20 parts of water is a very effective 
disinfectant. The carbolic acid is not readily soluble: 
for this reason it should be carefully dissolved in warm water. 
When garments are to be disinfected they should remain in 
the solution prepared as directed above for not less than 
one hour. 

Carbolic acid is poisonous, expensive and will destroy 
the spores of anthrax and other spore-forming bacteria. It 
has several advantages in that it destroys non-spore-bearing 
bacteria, is little interfered with by albuminous matter, 
when diluted does not destroy fabrics nor corrode metals, 
and that it is easily obtained at any drug store. 

Crude Carbolic Acid. Crude carbolic acid is very exten- 
sively used as a disinfectant. It is variable in its composi- 



INSECTICIDES, FUNGICIDES AND DISINFECTANTS 223 

tion and uncertain in its effects. It consists of a mixture of 
coal tar oils, cresol and a very little phenol. The oil has 
practically no disinfectant properties, although the odor is 
popularly considered an indication that disinfection is being 
accomplished. Its value as a disinfectant depends on the 
content of cresol. When the cresol content is known, the 
material should be diluted until it contains 2 per cent of 
that acid. 

Cresol (CHsCgHUOH), tricresol, straw-colored carbolic 
acid, or liquid carbolic acid as it is variously termed, is found 
on the market in various degrees of purity. Cresol as de- 
scribed by the United States Pharmacopoeia is a colorless 
liquid having an odor similar to carbolic acid. On account 
of a small amount of impurities it is usually sold of a 90 to 
98 per cent purity. It should not contain less than 90 per 
centcresylic acid, as the cresol containing less amounts usually 
carries enough coal tar oil to interfere with the solution of 
the cresol in water. This material is relatively cheap and 
well suited to disinfect yards, barns, and cars. The solu- 
tion used for disinfecting should contain about 2 per cent of 
cresol, which is said to be more effective than 5 per cent 
carbolic acid. It is applied the same as the carbolic acid 
solution. This material is not readily soluble in water, 
hence care must be exercised to get a strong enough solution. 
Its advantages are that it is cheap, does not destroy fabrics 
or metals, is more effective than carbolic acid for destroying 
spore -forming bacteria, and its action is not hindered by 
albuminous substances. 

Cresol is made more soluble by mixing with an equal part 
of linseed-oil-potash soap. Care must be taken to assure the 
presence of 50 per cent of actual cresol in the mixture. 
There should be 3 or 4 per cent of cresol in this sort of a 
mixture when used for disinfecting, hence an increase in cost 
over the straight cresol solution. 

Bichloride of Mercury. Bichloride of mercury (HgCl2) 
is a white crystalline, poisonous substance. It is prepared 



224 CHEMISTRY OF FARM PRACTICE 

in tablet form mixed with ammonium chloride (NH4CI), 
which facilitates its solubility. It is used in the proportions 
of 1 to 500 or 1 to 1000. It combines with albuminous sub- 
stances and is rendered inert. This material is a powerful 
germicide, but it is a deadly poison. 

All disinfectants are selected because of their chemical 
activity, and care should be exercised in handling them 
because of their poisonous nature. The remnants after use 
should be destroyed rather than stored. 



CHAPTER XXI 
PAINTS AND WHITEWASHES 

165. Paints. Few farmers realize fully the economic 
value of paint on farm buildings and farm machines; its 
use is sometimes regarded as a luxury that may readily be 
dispensed with. Paint not only improves the appearance of 
the various objects to which it is applied, but it has a greater 
value in preventing or delaying the rusting or decaying of 
both machinery and buildings, thereby increasing their 
length of service. One does not have to be a skilled painter 
to do the ordinary painting on the farm. With the aid of 
a few inexpensive utensils, paint may readily be applied. 

Paint consists of a pigment or of several pigments held 
in suspension by a liquid, or vehicle, as it is called. If the 
paint is to be used for outside work it must be insoluble in 
water and possess a high resistance to the chemical action of 
atmospheric elements. Pigments are stable organic bodies 
or mineral compounds which are used to impart either a 
protective covering or a color or both, by mechanical ad- 
hesion or by admixture with the substance to be painted. 
The color of a pigment is dependent upon the amount and 
kind of light that it reflects. It should be opaque if it is 
desired to conceal the surface to which it is applied. The 
vehicle is the liquid portion of the paint and is usually 
a drying oil; sometimes water with gum or size is used 
for inside work. Linseed oil seems to be the best oaint 
vehicle. 

166. Drying Oils. The so-called drying oils are named 
for their peculiar property of hardening. When linseed 
oil, and any one of a number of other oils having somewhat 
similar properties, is spread in a thin layer over a surface, 

225 



226 CHEMISTRY OF FARM PRACTICE 

it will dry and set in a hard film, due to the absorption of 
oxygen from the atmosphere. Corn oil and soybean oil, 
to a limited extent, behave in a similar manner. The dry- 
ing of these oils is aided by sunlight and hindered by mois- 
ture; it does not occur in the absence of oxygen. Boiled 
oil dries more quickly than raw oil. 

167. Driers. The drying of paints may be hastened by 
certain compounds of lead and manganese which are known 
as driers. When the drier is applied in the form of a liquid 
it is known as a Japan drier. The use of a small amount 
of a drier seems more effective than when a large amount is 
applied. With an excessive amount of drier the film pro- 
duced is not so durable. Some pigments, red lead for 
example, act as driers as well as pigments. It is generally 
believed that the greater the proportion of the pigment the 
more resistance the film will show, provided that all of the 
particles of the pigment are covered with oil. 

For thinning paint to make it work easier, certain vola- 
tile materials are used, such as turpentine or benzine. 

168. White Pigments. White lead is the most important 
of all pigments. This material is a basic lead carbonate in 
which there are two molecules of lead carbonate to one mole- 
cule of lead hydroxide (2PbC03-Pb(OH)2). White lead 
is very heavy, being 6.47 times heavier than the same volume 
of water. Its great value as a pigment is due to its covering 
power, its permanency, and to the readiness with which it 
mixes with other pigments. Like all lead compounds it is 
poisonous. 

Sublimed White Lead. This has recently come into ex- 
tensive use. It has good covering power and color, mixes 
well with pigments containing sulphur, and is more durable 
in sea air than is white lead. With linseed oil it dries rapidly, 
forming a tough, impervious coating. Sulphur fumes will 
not affect it quickly. For these reasons it is frequently 
used as a substitute for white lead. It is composed of 75 
per cent lead sulphate, 20 per cent lead oxide and 5 per cent 



PAINTS AND WHITEWASHES 227 

zinc oxide. Whether it is a mixture or a compound is not 
determined. 

Zinc Oxide or Chinese White. This material works well 
in oil, requiring a very large amount, approximately 20 per 
cent of its weight, and is used as a house paint and as 
an enamel for inside surfaces as bathtubs, plumbing, etc. 
It is the whitest of all the paint pigments. It will not 
collect dust as much as does white lead. When mixed with 
white lead it retards or entirely prevents the discoloration 
of the latter by hydrogen sulphide. 

Lithopo?ie. This is a mixture of zinc sulphide and barium 
sulphate, heated, suddenly chilled and then ground. This 
material has a brilliant color, and more body than has white 
zinc. It is permanent, is fine in texture and mixes well 
with oil and other pigments, except those containing lead or 
copper. It is used advantageously as a marine paint. It is 
largely used in the oilcloth industry. 

Barytes. Barium sulphate is very heavy, and may be 
mixed with all pigments, but it has little body, dries slowly, 
and does not mix well with oil. When used as an adulterant 
of white lead its use is to be avoided. When applied in 
limited amount as an extender in mixed paint, it imparts 
desirable qualities. It is used by the United States Navy 
as a basis for battle-ship gray. 

169. Green Pigments. Brunswick green is oxychloride 
of copper. This pigment works well with oil, has a fair 
covering power, but is rather pale in color. Other pigments 
sold under this name consist of a mixture of Prussian blue, 
chrome yellow, and barytes in varying proportions. They 
work well in oil, have good covering power, and last fairly 
well, but they cannot be used with alkaline substances, com- 
pounds of sulphur, or in the presence of hydrogen sulphide. 

Chrome greens are mixtures of chrome yellow and Prussian 
blue. They are yellowish green in color, mix well with oil 
and with other colors, have good covering power, and are 
permanent. 



228 CHEMISTRY OF FARM PRACTICE 

170. Blue Pigments. Ultramarine blue is probably a 
double silicate of sodium and aluminum and sulphide of 
sodium. The composition is, however, somewhat variable. 
It is the most important blue pigment. Ultramarine is 
very sensitive to acids. In addition to its use as a pig- 
ment in paints it is used in coloring wall-paper, in calico 
printing and for neutralizing yellow-colored sugar, paper 
pulp, and cloth. It may also be made by grinding up the 
mineral lapis lazuli. This is not so easily affected by acids 
but has not so brilliant a color. 

Prussian blue is ferrocyanide of iron. It is not affected 
by acids, mixes well with oil, but the color is destroyed by 
alkalies. It has good coloring powers, but is transparent 
and lacks body. 

171. Red Pigments. Red lead is lead tetroxide (PD3O4). 
It is a pigment of great brilliancy when a good compound 
is secured and it has remarkable covering power. It is 
made by heating litharge (PbO). 

Iron reds are prepared in large quantities as by-products 
from other manufactures. They are valuable pigments, 
being very permanent. These pigments are not very bright, 
but they have several advantages; they work well in oil, 
mix with other pigments, have good body and are cheap. 
They are compounds of ferric oxide (Fe20s). 

Vermilion is mercuric sulphide (HgS). It is a heavy, 
opaque, brilliant pigment which does not work well with 
oil on account of its weight. It is quite permanent, and 
readily affected by either acids or alkalies, but it is very 
expensive. 

172. Yellow Pigments. Chrome yellows are chromate 
of lead, zinc, or barium, each having a characteristic shade. 

Lead chromate is a brilliant yellow which mixes well with 
oil and has great covering powers. If treated with a caustic 
alkali, its color changes to orange or red. 

Yellow ochres are natural mineral products which vary in 
color, the color being due to hydrated oxide of iron. 



PAINTS AND WHITEWASHES 229 

173. Brown Pigments. Umbers are ochres containing 
a large amount of manganese. The best umber comes 
from Cyprus; it is very permanent, has good covering 
power, and mixes well with other pigments. It is neither 
affected by acids nor alkalies and it is very cheap. 

Vandyke browns are mixtures of iron oxides and organic 
matter. They are permanent, mix well with other pig- 
ments, and have good body. 

174. Black Pigments. Lampblack, as well as the other 
black pigments, has carbon for its basis. Lampblack is 
permanent, of good covering power, and fine grained. It is 
difficult to mix with water or oil and dries slowly. 

175. Mixing Paints. The main object in mixing paint 
is to get every particle of the pigments in contact with the 
vehicle. The pigments are purchased dry or in the paste 
form mixed with a small amount of the vehicle. The 
latter form is usually preferable, because the pigment has 
been ground in a small amount of the vehicle in preparation 
and its dilution is easier than the suspension of the dry 
pigment. 

A small hand mill can be purchased for about $10 that 
is satisfactory for mixing paints. For small jobs the ready 
mixed paints are more economical. 

176. Whitewashes. Government whitewash is prepared 
by slaking one-half bushel of good quicklime in hot water, 
keeping it covered while slaking. Strain and add 4 quarts 
of salt, dissolved in warm water, 3 pounds of ground rice 
boiled to a thin paste, \ pound Spanish whiting, and 1 pound 
of clear glue, dissolved in warm water. Mix and let stand 
for several days. Keep the wash thus prepared in a kettle 
or portable furnace, and when used put it on as hot as possi- 
ble with a painter's brush or a whitewash brush. This 
wash may be made in quantities and heated as needed, but 
it should be put on hot. 

Factory whitewash is used for interior work. Slake 1 
bushel (62 pounds) of quicklime with 15 gallons of water; 



230 CHEMISTRY OF FARM PRACTICE 

keep the barrel covered and stir occasionally. Beat up 
separately 2J pounds of rye flour in \ gallon of cold water, 
then add 2 gallons of boiling water. Then dissolve 2\ 
pounds of rock salt in 2\ gallons of hot water. Pour the 
last two preparations into the first. 

Waterproof Whitewash. Slake 1 bushel of quicklime 
with 12 gallons of hot water. Then dissolve separately 
2 pounds of common table salt and 1 pound of zinc sulphate 
in 2 gallons of boiling water. Pour the last preparation into 
the first and add 2 gallons of skimmed milk. 

177. Special Ingredients for Whitewash. An ounce of 
alum added to each gallon of lime whitewash increases its 
sticking properties. A pint of molasses to 5 gallons of white- 
wash renders the lime more soluble and increases its pene- 
tration. Silicate of soda solutions aid in fireproofing, 
while 1 pound of bar soap dissolved and added to 5 gal- 
lons of whitewash gives it a gloss. 

178. Calcimine. The basis of calcimine is whiting, or 
carbonate of lime. This material is carried in water as a 
vehicle and is made to adhere by the use of glue. Damp- 
proof calcimine is prepared by thoroughly mixing 16 pounds 
of Paris white or extra gilders' whiting with 1 gallon of boil- 
ing water. Soak separately \ pound of white sizing glue 
for four hours in | gallon of cold water, then dissolve by 
healing on a water bath. Also, dissolve 4 ounces of sodium 
phosphate in 1 pint of boiling water. Mix the last with the 
first and add the second. For tinting use yellow ochres, 
sienna, umbers, Venetian red, para-red, maroon, oxid, 
ultramarine blue, ultramarine green, chromium oxide, or 
bone black, none of which is affected by lime. 

If lampblack is used for tinting, it must be stirred in hot 
water containing a little soap or in cold water containing 
a little borax, the alkali serving to overcome the greasy 
nature of the lampblack. 

179. Varnishes. A varnish is a dissolved resin, or a 
drying oil, which, when exposed to the air, becomes hard 



PAINTS AND WHITEWASHES 231 

and impervious to air and water. After the varnish is 
applied, the solvent evaporates, leaving the resin, or the oil 
oxidizes and dries. 

Spirit varnish consists of resin dissolved in alcohol, 
petroleum spirits or some other volatile solvent. Turpentine 
varnishes are those in which turpentine is the solvent used. 
Linseed oil varnishes may consist of linseed oil alone, or 
resin and turpentine may be added. The addition of tur- 
pentine tends to overcome the tendency to scale off. The 
most important varnishes are made with shellac, while 
mastic, sandarac, and dammar are sometimes used. 

Oil Varnish. The greater part of the varnishes made are 
compounded of linseed oil, resin and turpentine. Tur- 
pentine varnishes dry slowly but they are tough and flexible. 
Linseed varnishes are the most important, but they do not 
show the surface brilliancy that some other varnishes show. 

180. Shellac. Shellac is a form of the resin lac which is 
produced by the bite of certain insects on the small twigs 
of several species of trees which grow in the East Indies. 
The insects feed on the plant sap and exude the lac, which 
finally covers the insect and her eggs. The twigs bearing 
these exudations are collected and appear commercially as 
stick lac. The crude material is first treated by macerating 
in warm water to remove a red dye-stuff that it carries. This 
material is sold as lac-dye, and the residue from the macera- 
tion is known as seed-lac. This is refined by melting and 
straining through muslin bags. The melted lac is poured 
in thin films over cold surfaces, to which it will not adhere, 
and is allowed to cool. These flakes are sold as shellac. 
Shellac is completely soluble in caustic alkalies and in borax 
solutions. It is partly soluble in alcohol, turpentine, chloro- 
form or ether. 

181. Glue. Glue is a product of the decomposition of 
animal connective and elastic tissues. It contains two essen- 
tial constituents, gluten and chondrin. The former has 
great adhesive properties and the latter is adhesive to a less 



232 CHEMISTRY OF FARM PRACTICE 

extent. Glues are variously termed hide glue, bone glue 
and fish glue, due to the source from which they are derived. 
Bone glue and hide glue have essentially the same general 
characteristics, while fish glue has less jellying properties. 
Liquid glue is made by treating fish glue with acetic, hydro- 
chloric, or nitric acid, any one of which will cause the loss of 
the property of gelatinizing when cold. 



CHAPTER XXII 

MATERIALS PRODUCING HEAT AND LIGHT— FIRE 
EXTINGUISHERS 

182. Petroleum. Crude petroleum is found in enormous 
quantities in oil-bearing rock strata. The world's product ion 
of this most important material in the year 1912 was 
350,000,000 barrels. California, Oklahoma, Illinois, West 
Virginia, Texas, Louisiana, Ohio and Pennsylvania are the 
principal sources of supply in this country, which furnishes 
62 per cent of the world's production. In other countries 
Russia is the largest producer (19 per cent) . Petroleum from 
the Appalachian fields is a thick greenish liquid. It is 
composed of a mixture of many hydrocarbons, some of which 
contain sulphur. Petroleum is economically conveyed 
through pipe lines, one of these extending from the Okla- 
homa field via Kansas City and Chicago to the seaboard, 
a distance of 1600 miles. 

Petroleum is the source of very many substances of great 
value, as for the production of illumination, for fuel and for 
lubrication. By processes of distillation at different tem- 
peratures these products are separated from the petroleum 
and, passing off as vapors, are turned into liquids by conden- 
se t ion. In the distillation the products of low-boiling 
points coming off first arc in succession petroleum-ether, 
gasoline, naphtha, benzine and kerosene. The remaining 
oil is then chilled and the solid waxes and paraffins are 
separated by filtering. The liquid remainder is then dis- 
tilled fractionally into fuel oils and light and heavy lubrica- 
ting oils. All these products from petroleum and many 
others not mentioned arc composed of mixtures of hydro- 
carbon compounds having formulas varying from C5H12 con- 

233 



234 CHEMISTRY OF FARM PRACTICE 

tained in petroleum-ether to C2&H56 contained in paraffin. 
Within recent years, petroleum in its unrefined con- 
dition has come into use as a fuel for steamships and 
for manufacturing purposes, competing successfully with 
coal. 

183. Kerosene. This is the most commonly used source 
of illumination in rural districts. Its use as a means of 
temporary or quick heating is both economical and conve- 
nient. Kerosene is a mixture of seven hydrocarbons ranging 
from C10H22 to C16H34 with specific gravity varying accord- 
ing to the grade of the oil, from 0.795 to 0.810. In the 
trade kerosene oil is classed according to color and to the 
temperature at which the oil gives off enough inflammable 
vapor to produce a momentary flash when a flame is applied. 
The grades of color are ''Standard White" (pale yellow), 
"Prime White" (straws) and "Water White" (colorless). 
The flash tests required in different states of the United 
States vary from 100° F. to 120° F. Water White oil with 
flash-point of 150° F. is known as Head Light Oil. Low 
flash-points in kerosenes indicate the presence of benzines 
or naphthas whose inflammability makes the oil dangerous 
for use in lamps. 

184. Gasoline. This is formed by the distillates of pe- 
troleum that pass off at lower temperatures than that 
required for kerosene. These are different grades of gaso- 
lines, but those most used in automobile engines have dis- 
tilling temperatures varying between 70 and 90° C. cor- 
responding to hydrocarbons with the formulas C\;Hi4 and 
C7H1G. The volatility of gasoline enables it easily to bo 
converted into vapor which when it is mixed with air be- 
comes highly explosive and therefore suitable for the internal 
combustion demanded by engines of the automobile and 
steam-launch type. 

185. Acetylene. When petroleum oil is " cracked " 
by dropping upon plates heated to a high temperature, 
among the decomposition products is Acetylene (C2H2). 



MATERIALS PRODUCING HEAT AND LIGHT 235 

It can be more easily produced by dropping water upon 
calcium carbide (CaC2). The carbide may be produced 
by heating to a high temperature coke (C) and quicklime 
(CaO). This reaction is represented as follows: 



3C + CaO = 


= Ca( 5 2 


+ CO. 


Carbon Quicklime 


Calcium 


Carbon 




carbide 


monoxide 



Water reacting with calcium carbide reacts as follows : 



CaC 2 


+ 


2H 2 = 


= Ca(OH) 2 


+ 


C2H2. 


Calcium 




Water 


Calcium 




Acetylene 


carbide 






hydroxide 







Acetylene burns with an extremely hot flame which in an 
ordinary burner of a fish tail pattern is smoky. A special 
burner devised so that two fine streams of acetylene mixed 
with air impinge one on the other will produce a very small, 
brilliant flame which, when analyzed, is found to resemble 
in quality sunlight much more nearly than any other illumi- 
nant. The equation represented by the chemical action in 
the flame is, 

C2H2 + 50 = 2C0 2 + H 2 0. 

Acetylene Oxygen Carbon Steam 

dioxide 

The range of the mixture of acetylene and air which will 
explode is much greater than that of other illuminating gases 
and the violence of the explosion is far greater than in the 
case of other illuminants, therefore mixtures of acetyl- 
ene and air are very dangerous. Nevertheless acetylene 
illumination is very efficient. Prest-O-Lite, generally used 
in automobile lights, is acetylene dissolved in acetone 
(CH 3 ) 2 CO. 

Acetylene decomposes, when heated, with the liberation 
of a large amount of heat. When this heat of decomposition 
is added to that produced when acetylene is burned in a 



236 



CHEMISTRY OF FARM PRACTICE 




Fig. 76.— Fire Extinguisher. (Figs. 76 
and 77, by permission of Mr. James 
C. Goddard, Philadelphia.) 



stream of oxygen, the 
temperature obtained is 
remarkably high. Such 
a flame will eat its way 
through a six-inch steel 
shaft in less than one 
minute. The steel frames 
of modern buildings may 
be rapidly taken apart 
by this flame. 

186. Fire Extinguish- 
ers. Fire extinguishers 
are effective means of 
extinguishing a fire be- 
fore it gains headway. 
The presence of such a 
contrivance may prevent 
a disastrous conflagration 
and will surely pay for 
itself in the peace of 
mind of the farmer and 
his family. A convenient 
form shown in Fig. 76 
consists of a heavy metal 
cylindrical container 
made to withstand a 
pressure of 350 pounds 
per square inch. The 
charge consists of a sat- 
urated water solution of 
1\ pounds of sodium bi- 
carbonate (cooking soda, 
NaCHOs), with which 
the cylinder is filled to 
the mark and 4 fluid 
ounces of sulphuric acid 



MATERIALS PRODUCING HEAT AND LIGHT 237 

in a glass bottle which is held in place by a metallic 
device which permits the acid to flow out when the ex- 
tinguisher is overturned. The arrangement of these 




Fig. 77. — Working parts of Fire Extinguisher. 

1. Position of acid bottle and decomposing cup C when the Underwriters 
Extinguisher is not in action. A, cage for acid bottle. B, movable support for 
opening cage. C, acid decomposing cup acting as bottle closure. D, upper pro- 
jection or guide stem, operating in socket F. E, lower projection or guide stem, 
operating in the neck of the acid bottle. F, socket for upper guide stem D. 
G, sulphuric acid, correct charge bottle half-full. (The two guide stems D and 
E center and hold the decomposing cup C in its true position at the mouth of 
the acid bottle, either while the extinguisher is at rest or in action, or in starting 
and stopping it.) . ' . 

2 Position of acid bottle and decomposing cup C, when the extinguisher 
is in action. H, decomposing cup C filled with acid, showing point where the 
chemicals come together, when the extinguisher is inverted. (It is at this point 
that the soda solution attacks and eats the acid out of the decomposing cup, and as 
decomposition takes place, a fresh supply of acid is fed from the bottle into the 
cup as fast as needed — but no faster — insuring uniform chemical action.) 

3 Shows the depth and interior of the porcelain acid decomposing cup C. 



materials inside the container is shown in Fig. 77. The 
reaction between the sulphuric acid and bicarbonate of 
soda rapidly generates carbon dioxide, which furnishes 
pressure, causing a mixture of the solution and gas to be 



238 CHEMISTRY OF FARM PRACTICE 

thrown with great force on the fire. The chemical action 
of the bicarbonate and acid is as follows : 

2NaHC0 3 + H2SO4 = 2C0 2 + 2H 2 + Na 2 S0 4 . 

To operate the extinguisher it is turned upside down and the 
contents played on the fire by means of the hose attached 
at the top of the cylinder when in operation. 



CHAPTER XXIII 
CONCRETE 

187. Use. Concrete is a mixture of cement, sand, 
crushed rock or gravel and water. It is a most excellent 
material for sidewalks, fence posts, foundations, floors and 
walls of buildings, beds or piers for machines and for struc- 
tures under water. It is manufactured in enormous quan- 
tities and its use for these and many other purposes is rapidly 
increasing. A hundred millions of barrels are produced in 
the United States annually. The rapid decrease of timber 
supply has made an urgent demand for a new building 
material which is amply met by the use of concrete. On 
account of its economy, durability and safety from fire loss 
and ease of manipulation it is superior to lumber, brick or 
building stone for construction purposes. The farmer with 
little assistance and at convenient times can use successfully 
this most excellent material. 

188. Cement Manufacture. Cement is a powdered, 
calcined intimate mixture which, before heating, contained 
in definite proportion limestone or marl or chalk (CaCOs), 
clay (HAlSi0 4 ), and sand (Si0 2 ). In the manufacture of 
Portland cement these materials are mixed in the proper 
proportions as shown by chemical analysis, pulverized so 
that it will pass through a sieve with 100 meshes to the inch, 
burned in inclined rotary steel cylinders from 60 to 150 feet 
long lined with firebrick. In these furnaces the final 
temperature rises to 1400° C.-1600 C. To the resulting 
clinker is added a small amount of gypsum, which seems to 
affect the time required for the setting of the cement, and 
the material finally is ground to a very fine powder. Natural 
cement made from rock which has the correct proportions 

239 



240 CHEMISTRY OF FARM PRACTICE 

of lime, clay and sand and manufactured by heating moder- 
ately and grinding was formerly made in large quantities 
in this country. Owing to the cheapness with which Port- 
land cement may be manufactured, with its properties 
governed by correct admixture, the natural cement is being 
replaced by the Portland cement. Portland cement when 
properly made is guaranteed to meet the standard fixed by 
the American Society for Testing Materials. 

189. Setting of Cement. Cement after the sintering 
process of the furnace seems to be a mixture of calcium 
silicate (CaSi0 3 ) and calcium aluminate (Ca3(A10 3 )2). The 
latter seems to be the active agent causing the setting of 
the cement when it is mixed with water. This hydrolysis 
may be expressed as follows: 

Ca 3 (A103)2+6H 2 = 2Al(OH)3+3Ca(OH)2. 

The calcium hydroxide, crystallizing, binds the particles of 
calcium silicate together, while the aluminium hydroxide fills 
the interstices and makes the mass compact and impervious. 
When water is added to cement, it becomes a soft, sticky 
paste and it will remain in this condition for about thirty 
minutes, when it begins to harden or set. To disturb the 
concrete after the setting is begun means a loss in the strength 
of the concrete. For this reason the concrete should be 
placed in position in less than thirty minutes after the cement 
is first wet. There are several precautions to be observed. 
A new cement should neither be exposed to the hot sun for 
any considerable length of time nor to freezing temperature. 
No material should be placed on the freshly made cement 
that will affect its color. The cement must be kept dry, 
before its use, because it readily absorbs moisture from the 
atmosphere when stored in damp places; this causes it 
to become lumpy and consequently worthless due to the 
setting of the cement. Lumps may sometimes be caused 
by pressure; these may often be broken up and the 



CONCRETE 241 

cement be as good as any, hence care should be taken to 
determine the cause of the lumping before discarding the 
cement. 

190. Sand. Sand constitutes a large part of concrete. 
It is extremely important to secure the proper kind of sand, 
which should be coarse, clean, hard, and free from other 
materials. The screening of the sand should be done at 
the source of supply. This is accomplished by screening 
what passes a J-inch sieve against a sieve containing forty 
meshes to the linear inch and set at an angle of 45°, using 
the portion retained by the sieve. 

The following test will show the proportions of sand, clay 
and loam in the source of supply of sand: Fill a pint pre- 
serving jar to the height of 4 inches with the sand and 
add water to within 1 inch of the top. The lid is then 
fastened and the jar is shaken for ten minutes, after which 
the contents of the jar are allowed to settle. The sand settles 
to the bottom and the clay and other material gather at 
the top. If more than one-half of clay and loam is present, 
the sand should be rejected. If other sand is not con- 
venient, the sand in question may be washed. When 
washing is required, a simple way is to build a board plat- 
form 10 to 15 feet long with a 12-inch fall. On the sides 
and lower end, 2 by 8-inch pieces should be nailed to hold 
the sand. The sand is spread on this platform to a depth 
of 3 or 4 inches and is washed by means of a hose, the water 
being applied at the elevated end of the platform and run 
through the sand and over the lower end. The impuri- 
ties in the sand should not amount to more than 10 per 
cent of the whole. 

191. Gravel. The gravel or crushed stone which con- 
stitutes a large part of the concrete should vary from that 
retained on a J-inch screen to those that pass a lf-inch 
ring. This material should be as free as possible from 
dirt and, if necessary, may be washed in the way suggested 
for sand. 



242 



CHEMISTRY OF FARM PRACTICE 



192. Quantity of Materials for a Given Mixture. Con- 
crete is a manufactured stone and the object is to fill the 
interstices between the gravel with sand and those between 
the sand particles with cement, hence the volume of con- 
crete is just about represented by the volume of crushed 
stone or gravel. A mixture consisting of one part by vol- 

'mm 



Cement 




—12- 
Stone 




Concrete 

Fig. 78. — Required quantities of cement, sand, and stone or gravel 
for a 1 : 2 : 4 concrete mixture and the resulting quantity of con- 
crete. (Bulletin 461, U. S. Dept. Agr.) 



ume of cement, and two parts of sand and four parts of stone 
or gravel, is often used. Table XXIV gives the quantities 
of the various materials for cement or concrete mixtures; 
the relative values are shown in Fig. 78. 

TABLE XXIV.— QUANTITIES OF MATERIALS AND THE 
RESULTING AMOUNT OF CONCRETE FOR A TWO- 
BAG BATCH. 

(Farmer's Bulletin 461, U. S. Dept. Agr.) 





Proportions 


M/ 








Sizes of Measuring Boxes 






by 


Parts. 




0J 
0) 


(Inside Measurements). 


+3 




















S 


^— 






o> 




QJ 


a> 


o 






3 O 


Kinds of 
Concrete 
Mixture. 






> 

a 


M 


3 


OS 


3 

o 

0) 


Sand. 


Stone or 
Gravel. 
















S-- 








«£ 3 




a 






C 




X 












<1> 

s 

O 


id 
a 
a 
to 


0> 

a 
o 


£ 

O 


a 

03 
0Q 


% 3 


C 
O 










1 :2 :4.. 


1 


2 


4 


2 


3f 


7^ 


8k 


2 feet by 2 
feet by 11£ 
inches. 


2 feet by 4 
feet by llf 
inches. 


10 


1 :2h :5. 


1 


2| 


5 


2 


4f 


9| 


10 


2 feet by 2 feet 
6 inches by 
11| inches. 


2 feet 6 inches 
by 4 feet by 
lli inches. 


12* 



CONCRETE 



243 



If the sand is very fine, the pore space will be increased, 
and therefore a little more cement will be required. The 
materials should be mixed until they assume a uniform 
color. If after thorough mixing the batch does not work 
well, the sand and cement does not fill the spaces between 




Fig. 79. — Concrete board and tools for making concrete. (Farmers' 
Bulletin 461, U. S. Dept. Agr.) 

the stones, the proportion of stone should be reduced in 
succeeding batches. 

TABLE XXV.— QUANTITIES OF MATERIALS IN 1 CUBIC 
FOOT OF CONCRETE 



Mixture of Concrete. 


Cement 
(by Barrels). 


Sand (by 
Cubic 
Yards). 


Stone or 
Gravel (by 

Cubic 
Yards). 


1-2:4 


0.058 
.048 


0.0163 
.0176 


0.0326 


1 • 2£ • 5 


.0352 







244 



CHEMISTRY OF FARM PRACTICE 



Table XXV gives the quantities of each material required 
in 1 cubic foot of concrete. With this data it is easy to 
calculate the amount of material for any given structure. 
A sack of cement contains 1 cubic foot of cement and four 
sacks constitute a barrel. 




Fig. 80. — Concrete watering trough. (From Howe's " Agricultural 

Drafting.") 



Example.* Let us suppose that the work consists of a 
concrete silo requiring in all 935 cubic feet of concrete, of 
which 750 cubic feet are to be 1:2:4 concrete, and 185 
cubic feet are to be 1 : 2\ : 5 concrete. Enough sand 
and cement are also needed to " paint " the silo inside 

* From U. S. Dept. of Agr. Bulletin, 461. 



CONCRETE 245 

and outside, amounting in all to 400 square yards of surface, 
with a 1.: 1 mixture of sand and cement. One cubic foot 
of 1 : 1 mortar paints about 15 square yards of surface and 
requires 0.1856 barrel of cement and 0.0263 cubic yard 
of sand. The problem thus works out as follows: 

Cement : Barrels. 

For the 750 cubic feet of 1 : 2 : 4 concrete (750 X 0.058) ... 43 . 5 
For the 185 cubic feet of 1 : 2\ : 5 concrete (185 X0.048) . . 8. ( .) 
For painting (400 4- 15 X0.1856) 4.9 

Total amount of cement 57 . 3 



Sand: Cubic Yds. 

For 750 cubic feet of 1 : 2 : 4 concrete (750X0.0163) 12.23 

For 185 cubic feet of 1 : 2\ : 5 concrete (185X0.0176) 3.26 

For painting (400^-15X0.0263) 70 

Total amount of sand 16.19 

Stone or gravel: 

For 750 cubic feet of 1 : 2 : 4 concrete (750X0.0326) 24.5 

For 185 cubic feet of 1 : 2| : 5 concrete (185 X0.0352) 6.5 

Total amount of stone or gravel 31.0 

Thus the necessary quantities of materials are about 
57| barrels of Portland cement, about 16| cubic yards of 
sand, and 31 cubic yards of stone or gravel. 

193. Mixing Concrete. In mixing concrete the sand is 
first spread over the mixing floor in a layer 3 or 4 inches in 
depth. The cement is then spread evenly over the sand. 
These materials are then mixed thoroughly with a shovel, 
the mixture is spread over the floor and the gravel is added. 
About three-fourths of the water to be used is then thrown 
as evenly as possible over the gravel layer and the materials 
are again thoroughly mixed with the shovel. Water should 
be added to the dry spots as the mixing proceeds, until 
the full amount has been used. After thoroughly mixing, 
the concrete is shoveled into a compact pile. 



246 CHEMISTRY OF FARM PRACTICE 

194. Placing the Concrete. Concrete should be placed 
immediately after mixing. Wooden forms to give the shape 
of the structure to be built, Fig. 81, are required and should 
be ready before the concrete is mixed. In placing the 
concrete, the shovel should be run down along the face of 
the form to press the gravel back and allow the cement to 



Fig. 81. — Forms for concrete watering trough. (From Howe's "Agri- 
cultural Drafting.") 

flow against the form, thus producing a smooth and finished 
surface when the form is removed. 

New concrete should not be exposed to the sun until 
after it has hardened for five or six days. The forms should 
be left in place till the concrete has " set " thoroughly. 
To permit removal of the forms, the surface should be wet 
daily. 



INDEX 



PAGE 

Acetylene 234 

Acids, characteristic properties of 24 

Air in soils G3 

Alunite 143 

Animal nutrition 174 

,V& digestible nutrients 176 

^ metabolism 176 

foods, classes of 174 

Anhydrides 27 

Atoms 3 

Babcock test for butter fat 204 

Bacteria, nitrogen fixing 64 

nitrifying 64 

Bases, properties 25 

Boracic acid, milk preservative 202 

detection of 204 

Butter 209 

composition of 210 

process 210 

Calcimine 230 

Calcium 42 

phosphate 23 

Carbohydrates 174 

Carbon 35 

Carbonates 66 

Carbon dioxide, effect on decay 65 

Cheese 210 

Combustion 8 

spontaneous 11 

Combustibles 8 

Compounds 13 

classes of 24 

nomenclature 29 

247 



248 INDEX 

PAGE 

Concrete 239 

cement manufacture 239 

gravel 241 

mixing 245 

placing 246 

sand 241 

setting of 240 

Crops, proper sequence of 86 

residues, composition of 85 

Digestibility, coefficient of 194 

Disinfectants 219 

lime 219 

chlorinate 219 

bichloride of mercury 225 

carbolic acid 222 

crude 222 

cresol 223 

formaldehyde 220 

sulphur 222 

Dissociation 28 

Elements 1 

groups of 24 

Equations 19 

Fats 175 

Feeding standard, Wolff-Lehman 177 

Feeds, composition 192 

concentrates , 184 

barley 184 

blood meal 188 

corn 184 

cottonseed meal 186 

dried brewers' grain 185 

dried fish 188 

linseed meal 187 

meat scraps 188 

oats 184 

peanuts 189 

rice, polish 186 

meal 186 

rye 185 

soybean meal 189 

wheat, bran 185 

middlings 185 



INDEX 249 



PAGE 



Fertilizers, incompatibilities, diagram showing Ki7 

mixing of I ( j.> 

advantages of home-mixing 152 

may be thoroughly mixed on farm 163 

educational value of home-mixing 165 

calculations of formulas 165 

Fire extinguishers 236 

Formalin, as a milk preservative 201 

detection of 203 

Formulas 1 6 

Food stuffs, average digestibility gg 

Fungi, injurious 212 

Fungicides 216 

Bordeaux mixture 216 

lime-sulphur 216 

self boiled 217 

sulphur; finely divided 217 

copper sulphate 218 

ammoniacal copper carbonate 219 

formaldehyde solutions 219 

Gases, diffusion of 67 

Gasolene 234 

Glue 231 

Hydrates 16 

Hydrogen 34 

Insects, injurious, classification 212 

Insecticides, for biting insects 213 

Paris green 214 

lead arsenate 213 

green arsenoid 215 

London purple 215 

for sucking insects 215 

kerosene emulsion 215 

soaps 215 

lime-sulphur 215 

nicotine solutions 215 

sulphate solutions 215 

carbon bisulphide 216 

hydrocyanic acid gas 216 

Ions 28 

Iron 42 

Kerosene 234 

Land, keeping covered 90 



250 INDEX 

PAGE 

Land plaster 105, 1 14 

Legumes 38 

Lime, agricultural 97 

application 101, 104 

burning on the farm 99 

dangers from use 100 

effects on soils 97 

machine for applying 104 

plants, improved by 103 

plant injured by 103 

shipping 100 

sources of 97 

Magnesium 42 

Manures, uses of 87 

effect of exposure to weathers 95 

factors affecting 92 

horse, properties of 95 

liquid 92 

plant food content of solid and liquid 93 

rate of application 96 

rotted, composition of 93 

Materials for bedding, composition of 93 

Matter, conservation of 13 

Milk, composition of 198 

ash, determination of 209 

city requirements 201 

condensed 211 

fat, determination of 204 

infected, dangers from 199 

preservatives 201 

solids, total, determination of 209 

specific gravity, determination of 208 

Mixtures, mechanical 14 

Molecules 3 

Nitrification 48 

Nitrogen, properties 37 

fixation of atmospheric 38 

importance of 120 

commercial, profitable 122 

selection of source of 122 

inorganic sources 124 

potassium nitrate 126 

sodium nitrate 127 



INDEX 251 

PAGE 

Nitrogen, inorganic sources, calcium nitrate 130 

ammonium sulphate 132 

organic sources 132 

dried blood 132 

ground fish 132 

tankage 132 

Peruvian guano 133 

hoof meal 133 

hides, horns, hair, etc 133 

wool 133 

bone 134 

cottonseed meal 134 

rapeseed meal 134 

linseed meal 134 

castor pomace 134 

calcium cyanamide 135 

Nutrition, animal 174 

Oils, drying 225 

Oleomargarine 210 

Osmosis 71 

Oxidation 7 

Oxygen 32 

importance of 66 

Paints 225 

driers 226 

mixing 229 

Petroleum 233 

Phosphate, bone 107 

Phosphoric acid, reverted 107 

Phosphorus 38 

presence in the soil 107 

as a limiting factor 108 

commercial sources 108 

phosphate rock 110, 118 

acid phosphate 112 

Thomas' phosphate 114 

bone 114 

mineral phosphate 115 

phosphatic guanos 116 

purchase and application ... 117 

Photosynthesis 73 

Pigments, white lead 226 

sublimed 226 



252 INDEX 

PAGE 

Pigments, white Chinese 227 

lithophonc 227 

barytes 227 

green, Brunswick 227 

chrome 227 

blue, ultramarine 228 

Prussian 228 

red, lead 228 

iron 228 

vermilion 228 

yellow, chrome 228 

chromate, lead 228 

ochres 228 

brown, umbers 228 

Vandyke 228 

black, lampblack 228 

Plant food, availability of 48 

source of 70 

forms of 152 

measuring requirements 152 

field tests 158 

Plant leaves, functions of 73 

leachings from 74 

food, gain and loss of 82 

Plants, root systems of 70 

Potassium 39 

Potash, salts, occurrence 137 

organic sources 140 

minor sources 140 

wood ashes as source of 140 

commercial salts 143 

Proteins 174 

Radicals 17 

Rations 179 

growth 179 

maintenance 180 

fattening 181 

milk-cows 182 

work animals 182 

calculations of 194 

Salts 26 

Shellac 231 

Soil components 59 



INDEX 253 

PAGE 

Soil analysis 152 

methods 153 

Soils, formation of 76 

composition of 79 

classification 81 

Sulphur 39 

Symbols 5, 6 

Temperatures, kindling. 9 

Valence 6, 14 

Varnishes 230 

spirit 231 

oil 231 

Water, properties of 44 

solvent, action of , 46 

drinking 49 

borne diseases 49 

spring 50 

shallow wells 50 

deep wells 51 

factors influencing attractiveness of 52 

hardness 52 

temporary, remedies for 53 

permanent, is removed 54 

filtered 55 

boiled 56 

distilled 56 

boiler 56 

treatment 58 

requirements of plants 59 

soil 60 

capillary 60 

gravitational 60 

Weights, atomic 3, 6 

molecular , 5 

Whitewash, Government 229 

factory 229 

waterproof 230 

special ingredients for 230 



THE WILEY TECHNICAL SERIES 

EDITED BY 

JOSEPH M. JAMESON 



A series of carefully adapted texts for usein technical, 
vocational and industrial schools. The subjects treated 
will include Applied Science; Household and Agricultural 
Chemistry; Electricity; Electrical Power and Machinery; 
Applied Mechanics; Drafting and Design; Steam; Gas 
Engines; Shop Practice; Applied Mathematics; Agriculture; 
Household Science, etc. 

The following texts are announced; others are being 
added rapidly: 

ELECTRICITY 

THE ELEMENTS OF ELECTRICITY; For Technical Students. 
By W. H. Timbie, Head of Department of Applied Science, 
Went worth Institute. xi+556 pages, 5% by 8. 415 figures. 
Cloth, $2.00 net. 

THE ESSENTIALS OF ELECTRICITY; A Text-book for Wire- 
men and the Electrical Trades. By W. H. Timbie, Wentworth 
Institute. Flexible covers, pocket size, xiii+271 pages, 5 by 7^. 
224 figures. Cloth, $1.25 net. 

CONTINUOUS AND ALTERNATING CURRENT MACHIN- 
ERY. By Professor J. H. Morecroft, Columbia University. 
ix+466 pages, 5% by 8. 288 figures. Cloth, $1.75 net. 

CONTINUOUS AND ALTERNATING CURRENT MACHIN- 
ERY PROBLEMS. By W. T. Ryan, E.E., Assistant Professor 
of Electrical Engineering, the University of Minnesota. 40 pages, 
5M by 8. Cloth, 50 cents net. 

5M 3-19-17 



ALTERNATING CURRENT ELECTRICITY AND ITS APPLI- 
CATION TO INDUSTRY. By W. H. Timbib, Head of 
Department of Applied Science, Wentworth Institute, and H. II . 
Higbie, Professor of Electrical Engineering, University of Mich- 
igan. First Course, x +534 pages, 5} by 8. 389 figures. Cloth, 
$2.00 net. 

Second Course, ix+729 pages. 5| by 8. 357 figures. Cloth 
$3.00 net. 

ELECTRIC LIGHTING. By H. H. Higbie, Professor of Electrical 
Engineering, University of Michigan. (In preparation.) 

HEAT AND HEAT ENGINEERING 

HEAT; A Text-book for Technical and Industrial Students. By 

J. A. Randall, Instructor in Mechanics and Heat, Pratt Institute. 
xiv+331 pages, 5}4 by 8. 80 figures. Cloth, $1.50 net. 

GAS POWER. By C. F. Hirshfeld, Professor of Power Engineering, 
Sibley College, Cornell University, and T. C. Ulbricht, formerly 
Instructor, Department of Power Engineering, Cornell University. 
viii+198 pages, 5M by 8. 60 figures. Cloth, $1.25 net. 

STEAM POWER. By C. F. Hirshfeld, Professor of Power Engi- 
neering, Sibley College, Cornell University, and T. C. Ulbricht, 
formerly Instructor, Department of Power Engineering, Cornell 
University, viii+419 pages. 5 34 by 8, 228 Figures. Cloth. 

HEAT AND LIGHT IN THE HOUSEHOLD. By W. G. Whitman, 
State Normal School, Salem, Mass. (In preparation.) 



MECHANICS AND MATHEMATICS 

ELEMENTARY PRACTICAL MECHANICS. By J. M. Jameson, 
Girard College, formerly of Pratt Institute, xii+321 pages, 5 by 
7%. 212 figures. Cloth, $1.50 net. 

MATHEMATICS FOR MACHINISTS. By R. W. Burnham, 
Instructor in Machine Work, Pratt Institute Evening School. 
vii+229 pages, 5 by 7. 175 figures. Cloth, $1.25 net. 

PRACTICAL SHOP MECHANICS AND MATHEMATICS. 

By James F. Johnson, Superintendent of the State Trade School, 
Bridgeport, Conn, viii+130 pages, 5 by 7. 81 figures. Cloth, 
$1.00 net. 



ARITHMETIC FOR CARPENTERS AND BUILDERS. By 

R. Burdette Dale, Assistant Professor in charge of Vocational 
Courses in Engineering and Correspondence Instruction, Iowa State 
College, ix+231 pages, 5 by 7. 109 figures. Cloth, $1.25 net. 



SHOP TEXTS 

MACHINE SHOP PRACTICE. By W. J. Kaup, Special Repre- 
sentative, Crucible Steel Company of America, ix+227 pages, 
5M by 8. 163 figures. Cloth, $1.25 net. 

PATTERN MAKING. By Frederick W. Turner and Daniel 
G. Town, Mechanic Arts High School, Boston, v+114 pages, 
5 by 7. 88 figures. Cloth, $1.00 net. 

PLAIN AND ORNAMENTAL FORGING. By Ernst Schwarz- 
kopf. Instructor at Stuyvesant High School, New York City. 
x+267 pages, 5% by 8. Over 400 figures. Cloth, $1.50 net. 



DRAFTING AND DESIGN 

DECORATIVE DESIGN. A Text-Book of Practical Methods. 
By Joseph Cummings Chase, Instructor in Decorative Design at 
the College of the City of New York and at Cooper Union Woman's 
Art School, vi+73 pages. 8 by 10%- 340 figures. Cloth, 
$1.50 net. 

AGRICULTURAL DRAFTING. By Charles B. Howe, M.E. 
viii+63 pages, 8 by 10%. 45 figures, 26 plates. Cloth, $1.25 net. 

ARCHITECTURAL DRAFTING. By A. B. Greenberg, Stuy- 
vesant Technical High School, New York, and Charles B. Howe, 
Bush wick Evening High School, Brooklyn. viii+110 pages, 
8 by 10%. 53 figures, 12 plates. Cloth, $1.50 net. 

MECHANICAL DRAFTING. By Charles B. Howe, M.E., 
Bushwick Evening High School, Brooklyn, x+147 pages, 8 by 
10%. 165 figures, 38 plates. Cloth, $1.75 net, 

ENGINEERING DRAFTING. By Charles B. Howe, M.E., 
Bushwick Evening High School, Brooklyn, and Samuel J. Berard, 
Sheffield Scientific School, Yale University. (In preparation.) 

DRAWING FOR BUILDERS. By R. Burdette Dale, Director 
of Vocational Course, Iowa State College, v + 166 pages, 8 by 
WA. 69 figures, 50 plates. Cloth, $1.50 net. 



AGRICULTURE AND HORTICULTURE 

FIELD AND LABORATORY STUDIES OF SOILS. By Pro- 
fessor A. G. McCall, Ohio State University, viii+77 pages, 
5 by 7. 32 figures. Cloth, 60 cents net. 

FIELD AND LABORATORY STUDIES OF CROPS. By Pro- 
fessor A. G. McCall, Ohio State University, viii+133 pages, 

5 by 7. 54 figures. Cloth, 85 cents net. 

SOILS. By Professor A. G. McCall, Ohio State University. (In 
preparation.) 

MARKET GARDENING. By Professor F. L. Yeaw, Oasis Farm 

6 Orchard Company, Roswell, New Mexico. Formerly Professor 
of Market Gardening, Massachusetts Agricultural College. vi+ 
120 pages, 5 by 7. 36 figures. Cloth, 75 cents net. 

THE CHEMISTRY OF FARM PRACTICE. By T. E. Keitt, 
Chemist of South Carolina Experiment Station, and Professor of 
of Soils, Clemson Agricultural College. xn-{-253 pages, 5}4 by 8. 
81 figures. Cloth, $1.25 net. 

STUDIES OF TREES. By J. J. Levison, Forester, Park Depart- 
ment, Brooklyn, N. Y. x+253 pages, 5% by 8. 156 half-tone 
illustrations. Cloth, $1.60 net. 

AGRICULTURAL DRAFTING. By Charles B. Howe, M.E. 
46 pages, 8 by 10%. 45 figures, 22 plates. Cloth, $1.25 net. 

PRACTICAL ENTOMOLOGY FOR SCHOOLS. By Dean E. D. 
Sanderson and Professor L. M. Peairs, West Virginia Univer- 
sity. (Ready May, 1917.) 



BIOLOGY 

LABORATORY MANUAL IN GENERAL MICROBIOLOGY. 

Prepared by the Laboratory of Bacteriology, Hygiene and Path- 
ology. Michigan Agricultural College, xvi+418 pages, 5| by 8. 
73 figures. Several tables and charts. Cloth, $2.50 net. 



THE LOOSE LEAF LABORATORY MANUAL 



A series of carefully selected exercises to accompany the texts 
of the Series, covering every subject in which laboratory or field 
work may be given. Each exercise is complete in itself, and is 
printed separately. 8 by lOh. 



Important Notice 
WILEY LOOSELEAF MANUALS 

The sale of separate sheets of the Laboratory Manuals of the Wiley 
Technical Series has been discontinued. These Manuals will, here- 
after, be sold only as a complete book with removal leaves. Descriptive 
literature will be sent on request. 



CHEMISTRY 

Exercises in General Chemistry. By Charles M. Allen, 
Head of Department of Chemistry, Pratt Institute. An 
introductory course in Applied Chemistry, covering a year's 
laboratory work on the acid-forming and metallic elements and 
compounds. 62 pages, 8 by 103^. 61 exercises. 
Complete in paper cover. Removal leaves. $1.00 net. 

Quantitative Chemical Analysis. By Charles M. Allen, Head 
of Department of Chemistry, Pratt Institute. 12 pamphlets. 
8 by 10^2. Complete in paper cover. Removal leaves. $1.00 net. 

Qualitative Chemical Analysis. By C. E. Bivins, Instructor in 
Qualitative Analysis, Pratt Institute. 11 pamphlets, supple- 
mented by Work Sheets by which the student is taught equa- 
tions and chemical processes. Complete with work sheets in 
paper cover. Removal leaves. $1.25 net. 

Technical Chemical Analysis. By R. H. H. Aungst, Instructor 
in Technical Chemistry, Pratt Institute. 19 pamphlets. 8 by 
103^. Complete. Removal leaves. 85 cents net. 

Exercises in Industrial Chemistry. By Dr. Allen Rogers, 
Instructor in Qualitative Analysis, Pratt Institute. (In prep- 
aration.) 



THE LOOSE LEAF LABORATORY MANUAL— Cant. 

MECHANICS AND HEAT 

Exercises in Mechanics. By J. M. Jameson, Girard College; 
Formerly of Pratt Institute. 52 exercises. Complete in paper 
cover. Removal leaves. 85 cents net. 

Exercises for the Applied Mechanics Laboratory. Steam; 
Strength of Materials; Gas Engines; and Hydraulics. By 
J. P. Kottcamp, M.E., Instructor in Steam and Strength of 
Materials, Pratt Institute. 8 by 1(% 58 exercises, with 
numerous cuts and tables. Complete in paper cover. Removal 
leaves. $1 net. 

ELECTRICITY 

Exercises in Heat and Light. By J. A. Randall, Instructor in 
Mechanics and Heat, Pratt Institute. 17 exercises, with nu- 
merous cuts and diagrams. 8 by 10J/£. Complete in paper 
cover. Removal leaves. 34 cents net. 

Electrical Measurements, A. C. and D. C. By W. H. Timbie, 
Head of Department of Applied Science, Wentworth Institute. 
52 Exercises. Complete in paper cover, 85 cents net. 

Elementary Electrical Testing. By Professor V. Karapetoff, 

Cornell University, Ithaca, N. Y. 25 exercises. Complete 
in paper cover. Removal leaves. 50 cents net. 

Electrical Measurements in Testing. (Direct and Alternating 
Current.) By Chester L. Dawes, Instructor in Electrical En- 
gineering, Harvard University. In charge of Industrial Elec- 
tricity, Franklin Union, Boston. 39 Exercises. Complete in 
paper cover. Removal leaves. 75 cents net. 

AGRICULTURE AND HORTICULTURE 

Studies of Trees: Their Diseases and Care. By J. J. Levison, 
M.F., Lecturer on Ornamental and Shade Trees, Yale University 
Forest School, Forester to the Department of Parks, Brooklyn, 
N. Y. 20 pamphlets, 8 by 1(% $1.00 net. A cloth binder for 
above sold separately. 50 cents net. 



THE LOOSE LEAF LABORATORY MANUAL— CW. 



Exercises in Farm Dairying. By Professor C. Larsen, De- 
partment of Dairy Husbandry, South Dakota State College. 
Loose leaf. 8 by 10£. 69 Exercises. Complete. Removal 
leaves. $1.00 net. 

Exercises in Agricultural Chemistry. By Professor T. E. Keitt, 
Clemson Agricultural College. {In preparation.) 

D RAWING 

AGRICULTURAL DRAFTING PROBLEMS. By Charles B. 
Howe, M.E. A Manual for Students of Agriculture to Sup- 
plement the Text in Agricultural Drafting. 26 plates. 8 by 
103^. In paper cover. Removal leaves. 50 cents net. 

THE ORDERS OF ARCHITECTURE. By A. Benton Greenberg. 
A Manual for Students of Architecture to Supplement the 
Text in Architectural Drafting. 20 plates. 8 by 103^. In paper 
cover. Removal leaves. 50 cents net. 



